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Though it has long been thought that the immune system is implicated in the pathophysiology of heat stroke, the underlying mechanisms are still poorly understood. As it has been reported in the literature that lymphocyte disturbance occurs in heat stroke patients or animals, we attempted to seek experimental evidence to define the role of lymphocytes in the pathophysiology of heat stroke. In our study, we used male Balb/c mice to establish a passive heat stroke model. We found that lymphocyte-deficient Severe combined immunodeficient (SCID) mice exposed to heat stress exhibited exacerbated heat stroke severity, which could be indicated by increased rates of mortality and serum levels of inflammatory cytokines compared to wildtype control mice. We further showed, through the depletion of T lymphocytes in wildtype mice and the transfer of wildtype lymphocytes into SCID mice, respectively, that T lymphocytes were both necessary and sufficient to alleviate the severity of heat stroke by inhibiting the early inflammatory response. Moreover, we found that the severity of heat injuries in heat-stressed wildtype mice showed great inter-individual variability, and the early number of T lymphocytes could be negatively associated with the severity of heat stroke. Our results suggest that lack of T lymphocytes could exacerbate the severity of heat stroke by augmenting inflammatory response, and the early circulating T lymphocytes may serve as a potential biomarker for the diagnosis of heat stroke., (Copyright © 2021. Published by Elsevier B.V.)

Objective: Natural killer (NK) cell-deficient mice are useful models in biomedical research. NOD/SCID mice have been used as a model of this type in research. However, the actual status of NK cells in NOD/SCID mice and CB17/SCID mice in comparison with that in BALB/c mice has not been sufficiently evaluated., Methods: Splenocytes from naïve or poly(I:C)-treated mice were isolated for phenotyping and analysis of cytotoxicity-related molecules and inhibitory receptors; for cytotoxicity assay, purified NK cells were also used., Results: The proportion of splenic NK cells did not differ significantly between NOD/SCID and CB17/SCID mice. The perforin levels in NK cells were similar between the poly(I:C)-treated CB17/SCID and NOD/SCID mice, while the granzyme B and NKG2A/C/E levels in NK cells from NOD/SCID mice were significantly lower than those from CB17/SCID mice. Moreover, the NKG2D and Ly49A levels in NK cells from NOD/SCID mice were higher than those from CB17/SCID. The splenocytes from CB17/SCID mice showed higher cytotoxicity than those from NOD/SCID mice, while the cytotoxicity of purified NK cells basically did not differ between the two strains. After in vitro stimulation with cytokines, the splenocytes from CB17/SCID mice showed higher IFN- γ production than those from NOD/SCID mice; however, NK cells did not., Conclusion: There was no significant difference in the proportion of splenic NK cells between CB17/SCID and NOD/SCID mice, and the function of NK cells was only partially compromised in NOD/SCID mice. Caution should be taken when considering the use of NOD/SCID mice as an NK-deficient model., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2021 Miao Miao et al.)

It is controversially discussed whether immune-deficient mice experience severity in the absence of infection. Because a comprehensive analysis of the well-being of immune-deficient mice under specific pathogen free conditions is missing, we used a multi-parametric test analyzing, corticosterone, weight, nest building and facial expression over a period of 9 month to determine the well-being of two immune-deficient mouse lines (recombination activating gene 2- and interferon gamma receptor-deficient mice). We do not find evidence for severity when comparing immune-deficient mice to their heterozygous immune-competent littermates. Our data challenge the assumption that immune-deficiency per se regardless of housing conditions causes severity. Based on our study we propose to use objective non-invasive parameters determined by laboratory animal science for decisions concerning severity of immune-deficient mice., Competing Interests: The authors declare that they do not have any competing interests.

Biological background data up to 11 weeks of age and tumorigenic susceptibility to xenotransplantation with HeLa cells were compared between severely immuno-deficient NOG and NSG mice. The body weight was lower in NOG mice than in NSG mice. Severe depletion of peripheral blood lymphocytes and lymphoid hypoplasia that are well-known characteristics of these mice were equally observed. No lymphoproliferative lesions developed in any mouse of either strain. The occurrence of ectopic exocrine gland and cyst was a common finding in the thymus of both strains. In addition, minimal spongiotic change was observed in the medulla oblongata and spinal cord in both strains, and its incidence in female NOG mice was a little higher than that in NSG mice. In the adrenal, subcapsular cell hyperplasia that is known as an age-related change in non-genetically modified mice developed earlier and its incidence was higher in NSG mice than in NOG mice. The development of female genital organs of NOG mice was slightly retarded in comparison with that of NSG mice. To evaluate tumorigenic susceptibility to xenotransplantation, female mice were implanted in the dorsal subcutis with 1×10 3 to 1×10 6 cells/head of HeLa cells, and were checked up to 16 weeks after implantation. As a result, there was no significant strain difference on tumor formation rate and tumor volume. In conclusion, the present study clearly demonstrated that NOG and NSG mice showed no distinct strain differences in either biological features or biological disadvantages.

Epizootic bovine abortion (EBA), or "foothill abortion," is the leading cause of beef cattle abortion in California and has also been reported in Nevada and Oregon. In the 1970s, the soft-shelled tick Ornithodoros coriaceus , or "pajaroello tick," was confirmed as the disease-transmitting vector. In 2005, a novel Deltaproteobacterium was discovered as the etiologic agent of EBA (aoEBA), recently named Pajaroellobacter abortibovis This organism cannot be grown in culture using traditional microbiological techniques; it can only be grown in experimentally-infected severe combined immunodeficient (SCID) mice. The objectives of this study were to perform a de novo genome assembly for P. abortibovis and identify and validate potential antigenic proteins as candidates for future recombinant vaccine development. DNA and RNA were extracted from spleen tissue collected from experimentally-infected SCID mice following exposure to P. abortibovis This combination of mouse and bacterial DNA was sequenced and aligned to the mouse genome. Mouse sequences were subtracted from the sequence pool and the remaining sequences were de novo assembled at 50x coverage into a 1.82 Mbp complete closed circular Deltaproteobacterial genome containing 2250 putative protein-coding sequences. Phylogenetic analysis of P. abortibovis predicts that this bacterium is most closely related to the organisms of the order Myxococcales, referred to as Myxobacteria. In silico prediction of vaccine candidates was performed using a reverse vaccinology approach resulting in the identification and ranking of the top 10 candidate proteins that are likely to be antigenic. Immunologic testing of these candidate proteins confirmed antigenicity of seven of the nine expressed protein candidates using serum from P. abortibovis immunized mice., (Copyright © 2017 Welly et al.)

Background & Objectives: Administration of ex vivo-expanded human bone marrow-derived mesenchymal stromal cells (hBMMSC) obtained from single donors has shown therapeutic benefits in both preclinical and clinical studies. In this study, the safety, toxicity and biodistribution profiles of a pooled hBMMSC population, produced from three healthy donors were assessed in rodent and non-rodents., Methods: The pooled hBMMSC population was characterized by their expression of various cell surface markers, differentiation potential and immunomodulatory activity. To establish in vivo safety of the pooled cells, these were administered by various injection routes into rodents and non-rodents to determine overall toxicity, biodistribution and tumorigenic potential in a series of preclinical studies., Results: Single injections of hBMMSC at various doses through intravenous or intramuscular routes did not cause toxicity in rats and rabbits. In addition, repeat administration of hBMMSC was also well tolerated by rats, and no prenatal toxicity was observed by multiple administration in the same animal species. Ex vivo-expanded and cryopreserved hBMMSCs did not induce tumour formation in severe combined immunodeficient (SCID) mice., Interpretation & Conclusions: Our results showed that the pooled hBMMSC population was non-toxic, non-teratogenic and non-tumorigenic in animals. Further studies need to be done to find out if it can be safely administered in human patients.

Mycobacterium avium (M. avium) causes significant pulmonary infection, especially in immunocompromised hosts. Alveolar macrophages (AMs) represent the first line of host defense against infection in the lung. Interferon gamma (IFN-γ) activation of AMs enhances in vitro killing of pathogens such as M. avium We hypothesized that airway delivery of AMs into the lungs of immunodeficient mice infected with M. avium will inhibit M. avium growth in the lung and that this macrophage function is in part IFN-γ dependent. In this study, normal BALB/c and BALB/c SCID mice received M. avium intratracheally while on mechanical ventilation. After 30 days, M. avium numbers increased in a concentration-dependent manner in SCID mice compared with normal BALB/c mice. Airway delivery of IFN-γ-activated BALB/c AMs or J774A.1 macrophages overexpressing IFN-γ into the lungs of SCID mice resulted in a significant decrease in M. avium growth (P < 0.01, both comparisons) and limited dissemination to other organs. In addition, airway delivery of IFN-γ activated AMs and macrophages overexpressing IFN-γ increased the levels of IFN-γ and TNF-α in SCID mice. A similar protective effect against M. avium infection using J774A.1 macrophages overexpressing IFN-γ was observed in IFN-γ knockout mice. These data suggest that administration of IFN-γ activated AMs or macrophages overexpressing IFN-γ may partially restore local alveolar host defense against infections like M. avium, even in the presence of ongoing systemic immunosuppression., (© 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

Percutaneous coronary intervention is widely adopted to treat patients with coronary artery disease. However, restenosis remains an unsolved clinical problem after vascular interventions. The role of the systemic and local immune response in the development of restenosis is not fully understood. Hence, the aim of the current study was to investigate the role of the human immune system on subsequent neointima formation elicited by vascular injury in a humanized mouse model. Immunodeficient NOD.Cg-Prkdc scid IL2rg tm1Wjl (NSG) mice were reconstituted with human (h)PBMCs immediately after both carotid wire and femoral cuff injury were induced in order to identify how differences in the severity of injury influenced endothelial regeneration, neointima formation, and homing of human inflammatory and progenitor cells. In contrast to non-reconstituted mice, hPBMC reconstitution reduced neointima formation after femoral cuff injury whereas hPBMCs promoted neointima formation after carotid wire injury 4 weeks after induction of injury. Neointimal endothelium and smooth muscle cells in the injured arteries were of mouse origin. Our results indicate that the immune system may differentially respond to arterial injury depending on the severity of injury, which may also be influenced by the intrinsic properties of the arteries themselves, resulting in either minimal or aggravated neointima formation.

Sentinel exposure to soiled bedding is frequently used for health monitoring of mice housed in individually ventilated cage systems (IVCS). Despite its advantages, the use of soiled bedding sentinels (SBSs) is far for being a reliable method. Two studies were conducted to evaluate the sensitivity of immunodeficient SBSs NOD.CB17-Prkdc(scid)/NCrHsd (NOD SCID) against two immunocompetent outbred strains, Hsd:ICR (CD-1) and RjOr1:Swiss (Swiss) to pinworm detection in IVCS-housing. Four different diagnostic methods were used: perianal tape test, fecal flotation, plate method and histology. Positivity was considered if at least one of the techniques used was positive. In the first study NOD SCID were more sensitive than CD-1 SBSs (P < 0.05), and except for the fecal flotation test performed at week 6, all the diagnostic methods were more sensitive with NOD SCID mice (P < 0.05). In the second study differences between the Swiss and NOD SCID mice were less obvious (P = 0.08). When compared separately, the different diagnostic methods, except for the fecal flotation test, were all more sensitive in the NOD SCID mice (P < 0.05). In addition, the anal tape test in the Swiss SBSs was more sensitive at week 7 than at week 15 (P < 0.05). In conclusion, combining various diagnostic techniques and samplings at week 7 post-exposure with non-invasive methods increases the rate of pinworm detection. Immunodeficient SBSs showed higher sensitivity than immunocompetent ones. Thus, use of immunodeficient SBSs is highly recommended in health control protocols., (© The Author(s) 2015.)

Significant advances in our understanding of the in vivo functions of human cells and tissues and the human immune system have resulted from the development of 'humanized' mouse strains that are based on severely immunodeficient mice with mutations in the interleukin-2 receptor common γ-chain locus. These mouse strains support the engraftment of a functional human immune system and permit detailed analyses of human immune biology, development and functions. In this Review, we discuss recent advances in the development and utilization of humanized mice, the lessons learnt, the remaining challenges and the promise of using humanized mice for the in vivo study of human immunology.

Immunodeficient mice reconstituted with human hematopoietic stem cells enable the in vivo study of human hematopoiesis. In particular, NOD-scid-IL2Rγ(null) engrafted mice have been shown to have reasonable levels of T and B cell repopulation and can mount T-cell dependent responses; however, antigen-specific B-cell responses in this model are generally poor. We explored whether developmental defects in the immunoglobulin gene repertoire might be partly responsible for the low level of antibody responses in this model. Roche 454 sequencing was used to obtain over 685,000 reads from cDNA encoding immunoglobulin heavy (IGH) and light (IGK and IGL) genes isolated from immature, naïve, or total splenic B cells in engrafted NOD-scid-IL2Rγ(null) mice, and compared with over 940,000 reads from peripheral B cells of two healthy volunteers. We find that while naïve B-cell repertoires in humanized mice are chiefly indistinguishable from those in human blood B cells, and display highly correlated patterns of immunoglobulin gene segment use, the complementarity-determining region H3 (CDR-H3) repertoires are nevertheless extremely diverse and are specific for each individual. Despite this diversity, preferential D(H)-J(H) pairings repeatedly occur within the CDR-H3 interval that are strikingly similar across all repertoires examined, implying a genetic constraint imposed on repertoire generation. Moreover, CDR-H3 length, charged amino-acid content, and hydropathy are indistinguishable between humans and humanized mice, with no evidence of global autoimmune signatures. Importantly, however, a statistically greater usage of the inherently autoreactive IGHV4-34 and IGKV4-1 genes was observed in the newly formed immature B cells relative to naïve B or total splenic B cells in the humanized mice, a finding consistent with the deletion of autoreactive B cells in humans. Overall, our results provide evidence that key features of the primary repertoire are shaped by genetic factors intrinsic to human B cells and are principally unaltered by differences between mouse and human stromal microenvironments.

Humanized mice, which refers to immunodeficient mice repopulated with the human immune system, are powerful tools for study in the field of immunology. It has been difficult, however, to generate these transgenic (Tg) mice directly from such strains as the NOD/SCID mouse. In this study, we describe a method developed by us for the generation of Tg mice on an NOD/SCID background. First, we obtained fertilized eggs efficiently by means of in vitro fertilization (IVF); then, we attempted to generate CAG-EGFP Tg mice on an NOD/SCID background, finding that delayed timing of the microinjection after the IVF improved the time to development of the two-cell-stage embryos and the obtainment of newborns. We successfully generated Tg mice and confirmed the germ-line transmission in the offspring. In conclusion, we established a novel system for directly generating transgenic mice on an NOD/SCID background. This novel system is expected to allow improved efficiency of the generation of humanized mice.

Pasteurella pneumotropica is an opportunistic pathogen in rodents. Natural infection in immunodeficient animals suggests that immunodeficiency is a major factor in P. pneumotropica pathogenesis. To understand this process, we performed clinical, pathological and bacteriological studies of immunodeficient NOD/ShiJic-scid/Jcl and immunocompetent Crlj:CD1 (ICR) mice experimentally infected with P. pneumotropica ATCC 35149. From 14 days postinoculation, some of P. pneumotropica-infected NOD/ShiJic-scid/Jcl mice developed clinical signs of weight loss. Three of 10 P. pneumotropica-infected NOD/ShiJic-scid/Jcl mice developed clinical signs of depression, ruffled coat, and weight loss and died at 27, 34, and 59 days postinoculation. At 35 days postinoculation, almost all P. pneumotropica-infected NOD/ShiJic-scid/Jcl mice had lung abscesses. The bacteria were isolated from the upper and lower respiratory tracts, including the lungs, and blood. In contrast, P. pneumotropica-infected ICR mice exhibited no clinical signs or lesions. The bacteria were isolated from the upper, but not the lower respiratory tracts. We developed an animal model for understanding host interactions with P. pneumotropica.

IgE-mediated hypersensitivity is central to the pathogenesis of asthma and other allergic diseases. Although neutralization of serum IgE with IgE-specific antibodies is in general an efficacious treatment for allergic asthma, one limitation of this approach is its lack of effect on IgE production. Here, we have developed a strategy to disrupt IgE production by generating monoclonal antibodies that target a segment of membrane IgE on human IgE-switched B cells that is not present in serum IgE. This segment is known as the M1' domain, and using genetically modified mice that contain the human M1' domain inserted into the mouse IgE locus, we demonstrated that M1'-specific antibodies reduced serum IgE and IgE-producing plasma cells in vivo, without affecting other immunoglobulin isotypes. M1'-specific antibodies were effective when delivered prophylactically and therapeutically in mouse models of immunization, allergic asthma, and Nippostrongylus brasiliensis infection, likely by inducing apoptosis of IgE-producing B cells. In addition, we generated a humanized M1'-specific antibody that was active on primary human cells in vivo, as determined by its reduction of serum IgE levels and IgE plasma cell numbers in a human PBMC-SCID mouse model. Thus, targeting of human IgE-producing B cells with apoptosis-inducing M1'-specific antibodies may be a novel treatment for asthma and allergy.

Activation of the immune system by ANG II contributes to the pathogenesis of hypertension, and pharmacological suppression of lymphocyte responses can ameliorate hypertensive end-organ damage. Therefore, to examine the mechanisms through which lymphocytes mediate blood pressure elevation, we studied ANG II-dependent hypertension in scid mice lacking lymphocyte responses and wild-type controls. Scid mice had a blunted hypertensive response to chronic ANG II infusion and accordingly developed less cardiac hypertrophy. Moreover, lymphocyte deficiency led to significant reductions in heart and kidney injury following 4 wk of angiotensin. The muted hypertensive response in the scid mice was associated with increased sodium excretion, urine volumes, and weight loss beginning on day 5 of angiotensin infusion. To explore the mechanisms underlying alterations in blood pressure and renal sodium handling, we measured gene expression for vasoactive mediators in the kidney after 4 wk of ANG II administration. Scid mice and controls had similar renal expression for interferon-gamma, interleukin-1beta, and interleukin-6. By contrast, lymphocyte deficiency (i.e., scid mice) during ANG II infusion led to upregulation of tumor necrosis factor-alpha, endothelial nitric oxide synthase (eNOS), and cyclooxygenase-2 (COX-2) in the kidney. In turn, this enhanced eNOS and COX-2 expression in the scid kidneys was associated with exaggerated renal generation of nitric oxide, prostaglandin E(2), and prostacyclin, all of which promote natriuresis. Thus, the absence of lymphocyte activity protects from hypertension by allowing blood pressure-induced sodium excretion, possibly via stimulation of eNOS- and COX-2-dependent pathways.

Purpose of Review: Update on humanized mouse models and their use in biomedical research., Recent Findings: The recent description of immunodeficient mice bearing a mutated IL-2 receptor gamma chain (IL2rgamma) facilitated greatly the engraftment and function of human hematolymphoid cells and other cells and tissues. These mice permit the development of human immune systems, including functional T and B cells, following engraftment of hematopoietic stem cells (HSCs). The engrafted functional human immune systems are capable of T and B cell-dependent immune responses, antibody production, antiviral responses, and allograft rejection. Immunodeficient IL2rgamma(null) mice also support heightened engraftment of primary human cancers and malignant progenitor cells, permitting in-vivo investigation of pathogenesis and function. In addition, human-specific infectious agents for which animal models were previously unavailable can now be studied in vivo using these new-generation humanized mice., Summary: Immunodeficient mice bearing an IL2rgamma(null) mutated gene can be engrafted with functional human cells and tissues, including human immune systems, following engraftment with human hematolymphoid cells. These mice are now used as in-vivo models to study human hematopoiesis, immunity, regeneration, stem cell function, cancer, and human-specific infectious agents without putting patients at risk.

Background: The lack of a suitable animal model to study viral and immunological mechanisms of human dengue disease has been a deterrent to dengue research., Methodology/principal Findings: We sought to establish an animal model for dengue virus (DENV) infection and immunity using non-obese diabetic/severe combined immunodeficiency interleukin-2 receptor gamma-chain knockout (NOD-scid IL2rgamma(null)) mice engrafted with human hematopoietic stem cells. Human CD45(+) cells in the bone marrow of engrafted mice were susceptible to in vitro infection using low passage clinical and established strains of DENV. Engrafted mice were infected with DENV type 2 by different routes and at multiple time points post infection, we detected DENV antigen and RNA in the sera, bone marrow, spleen and liver of infected engrafted mice. Anti-dengue IgM antibodies directed against the envelope protein of DENV peaked in the sera of mice at 1 week post infection. Human T cells that developed following engraftment of HLA-A2 transgenic NOD-scid IL2rgamma(null) mice with HLA-A2(+) human cord blood hematopoietic stem cells, were able to secrete IFN-gamma, IL-2 and TNF-alpha in response to stimulation with three previously identified A2 restricted dengue peptides NS4b 2353((111-119)), NS4b 2423((181-189)), and NS4a 2148((56-64))., Conclusions/significance: This is the first study to demonstrate infection of human cells and functional DENV-specific T cell responses in DENV-infected humanized mice. Overall, these mice should be a valuable tool to study the role of prior immunity on subsequent DENV infections.

SCID mice are a model of human severe combined immunodeficiency disease and are deficient in B cell function in addition to T cell function. Tumors from other species are easily transplanted into SCID mice and will grow without being rejected. We previously reported that the chemokine BRAK/CXCL14 is expressed in normal cells but its expression is down regulated in an in vitro cancer progression model, suggesting that it has the potential for antitumor activity. Here we report that the growth of BRAK/CXCL14 expression vector-transfected oral cancer cells was completely (100%) suppressed in SCID mouse xenografts even though mock-vector introduced control tumor cells grew well with 100% of animals developing tumors. In addition, suppression of xenografts was much faster and the rate was much higher in SCID mice than in T cell function-deficient nude mice. These data indicate the possibility that BRAK expression inhibits tumor cell establishment by regulating interactions between tumor stem cells and NK cells and/or suppressing formation of tumor microvessels.

Infection with human T-cell leukemia virus type 1 (HTLV-1) leads sometimes to the development of adult T-cell lymphoma/leukemia (ATL), which is invariably fatal and often associated with humoral hypercalcemia of malignancy. The transformation of infected CD4 T cells and the pathogenesis of leukemia have been studied with great limitation in tissue culture and patients. To better understand the pathogenesis and perform preclinical drug studies, animal models of ATL are urgently needed. In mice, inoculation of HTLV-1 cell lines mostly leads to development of localized lymphomas. To develop an ATL animal model with leukemic spread of ATL cells, mouse strains with different well-defined immune deficiencies were inoculated intraperitoneally with different HTLV-1-infected cell lines (ACH.2, C8166, MT-2, MET-1). Inoculation of MET-1 cells into NOD/SCID mice provided the best model system for slowly developing T-cell leukemia with multiple organ involvement. In leukemic mice, an increase in serum calcium levels correlated with expression of receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells ligand on leukemic cells and secretion of parathyroid hormone-related protein and interleukin-6. In contrast to the other cell lines that did not spread systemically, MET-1 expressed both the adhesion molecules CD11a (LFA-1alpha) and CD49d (VLA-4alpha) and produced or induced expression of matrix metalloproteinases 1, 2, 3, and 9, thus underlining the importance of these molecules in the spread of adult T-cell leukemia cells. The MET-1/NOD/SCID model will be useful for developing interventions against invasion and spread of leukemic cells and subsequent humoral hypercalcemia of malignancy.

Objective: To characterize uterine natural killer (uNK) cells in nonobese diabetic/severely compromised immunodeficient (NOD/SCID) mice and investigate the potential role of these cells in pregnancy tolerance., Design: An animal model-based study., Setting: Academic research center in a university., Animal(s): Syngeneic pregnant NOD/SCID mice were compared with non-immunodeficient BALB/c mice., Intervention(s): Induction of Toll-like receptor (TLR) agonists., Main Outcome Measure(s): Flow cytometric analysis was performed to detect the percentage of cell subsets, and standard (51)Cr release assay was performed to determine cytotoxicity., Result(s): The dominant subset of uNK cells in NOD/SCID mice is DX5 (CD49b)(+), asialo ganglio-N-tetraosylceramide(+), CD25(+), CD122(+), Thy-1 (CD90)(hi), c-kit (CD117)(hi), and interleukin-10(+). In addition, the percentage of interferon-gamma(+) subset was slightly increased in response to selected TLR agonists in the NOD/SCID mice, whereas the corresponding percentage in BALB/c mice could be increased dramatically. Such an effect could be abrogated by inhibitors, including LY294002, SP600125, and PD98059. The significant increase of interferon-gamma(+) NK cell percentage in BALB/c mice was concomitant with the increase of the embryo resorption rate. In contrast, the resorption rate in NOD/SCID mice was not significantly increased upon the induction of polyinosinic polycytidylic acid or lipopolysaccharide. As expected, the NK cells from NOD/SCID mice display a detectable but lower cytotoxicity than BALB/c, as determined by standard (51)Cr release assay. In addition, the uNK cells from NOD/SCID mice also display a hyposensitivity to lipopolysaccharide-induced production of inducible nitric oxide synthase., Conclusion(s): A considerable percentage of immature NK cells were detected at the fetomaternal interface in NOD/SCID mice. These cells were hyposensitive to the stimulation of selected TLR agonists. Such a status seemed to be beneficial for the maintenance of pregnancy.

Background: To investigate the role of T cells and natural killer (NK) cells in mediating corneal xenograft rejection in a pig-to-mouse model., Methods: Pig corneas were orthotopically transplanted into BALB/c, C57BL/6, nude, severe combined immunodeficiency (SCID), and NOD/SCID/gammac(null) (NOG) mice. Graft survival was clinically assessed by slit-lamp biomicroscopy and median survival times (MST) were calculated. The rejected grafts were histologically evaluated using antibodies against CD4, CD8, NK1.1, and F4/80., Results: The pig corneal xenografts were acutely rejected by BALB/c and C57BL/6 mice (MST 9.0 days), while nude, SCID and NOG mice rejected pig corneas in a more delayed fashion (MST 16.0, 16.4, and 16.9 days, respectively). The majority of infiltrating cells found in rejected grafts in C57BL/6 mice were macrophages and CD4(+) T cells, while CD8(+) T cells and NK cells were rarely found. The grafts in nude mice had markedly decreased inflammatory infiltration with small numbers of macrophages and CD4(+) T cells. Infiltration was even more modest in grafts in SCID and NOG mice., Conclusions: T cells play an important role in acute rejection of pig corneal xenografts in mice, although acute rejection is not solely the result of T-cell-mediated immunity. NK cells are less likely to be involved in the rejection process.

Epidemics of tick-borne encephalitis involving thousands of humans occur annually in the forested regions of Europe and Asia. Despite the importance of this disease, the underlying basis for the development of encephalitis remains undefined. Here, we prove the key role of CD8(+) T-cells in the immunopathology of tick-borne encephalitis, as demonstrated by prolonged survival of SCID or CD8(-/-) mice, following infection, when compared with immunocompetent mice or mice with adoptively transferred CD8(+) T-cells. The results imply that tick-borne encephalitis is an immunopathological disease and that the inflammatory reaction significantly contributes to the fatal outcome of the infection.

Ischemia reperfusion injury (IRI) is a common and important clinical problem in many different organ systems, including kidney, brain, heart, liver, lung, and intestine. IRI occurs during all deceased donor organ transplants. IRI is a highly complex cascade of events that includes interactions between vascular endothelium, interstitial compartments, circulating cells, and numerous biochemical entities. It is well established that the innate immune system, such as complement, neutrophils, cytokines, chemokines, and macrophages participate in IRI. Recent data demonstrates an important role for lymphocytes, particularly T cells but also B cells in IRI. Lymphocytes not only participate in augmenting injury responses after IRI, but could also be playing a protective role depending on the cell type and stage of injury. Furthermore, lymphocytes appear to be participating in the healing response from IRI. These new data open the possibility for lymphocyte targeted therapeutics to improve the short and long term outcomes from IRI.

We determined whether embryos derived from C.B-17/Icr-Prkdc(scid) (SCID) mice infected with mouse parvovirus (MPV) 1b and mated to MPV-naive B6C3F1 mice would transmit virus to naive recipient female mice and rederived progeny. Viral DNA was detected by quantitative PCR (qPCR) in lymphoid tissues, gonad, sperm, and feces of all MPV1b-inoculated SCID mice. Viral DNA was detected in 1 of 16 aliquots of embryos from infected male SCID mice and in 12 of 18 aliquots of embryos from infected female SCID mice. All recipient female mice implanted with embryos from infected SCID male mice and their progeny were negative by serology and qPCR. In contrast, 3 of 5 recipient female mice implanted with embryos from infected SCID female mice and 14 of 15 progeny mice from these recipients were seropositive by multiplex fluorescent immunoassay (MFI) for MPV capsid antigen (rVP2). All of these mice were negative by MFI for parvovirus nonstructural protein antigen (rNS1) and by qPCR, with the exception of 1 recipient female mouse that displayed weak rNS1 seroreactivity and low levels of MPV DNA in lymphoid tissues. Seroreactivity to rVP2 declined over time in all progeny mice from infected SCID female mice until all were seronegative by 20 wk of age, consistent with maternal antibody transfer. Given that the high levels of MPV contamination detected in our experimentally infected SCID mice are unlikely in naturally infected immunocompetent mice, these data indicate that embryo transfer rederivation is effective for the eradication of MPV from infected colonies.

A replication-defective herpes simplex virus (HSV)-2 vaccine, dl5-29, which is deleted for two essential early genes, UL5 and UL29, is highly immunogenic and protective in mice and guinea pigs. In a prior study, a derivative of HSV-2 dl5-29 termed dl5-29-41L, which has an additional deletion in UL41 (that encodes the virion-host shut-off protein), was more immunogenic and protective against challenge with wild-type HSV-2 in mice when compared with dl5-29. To determine if deletion of UL41 improves the efficacy of dl5-29 in protecting guinea pigs from HSV-2, animals were immunized with dl5-29, dl5-29-41L, or PBS. The geometric mean neutralizing antibody titers from the dl5-29 and dl5-29-41L recipients were comparable (10(1.97) and 10(2.19), respectively, p=0.15). After intravaginal challenge with wild-type HSV-2, the dl5-29-41L and dl5-29 recipients shed similar titers of HSV-2 from the vagina. Mean acute disease severity scores, numbers of recurrences during 3 months after infection, and latent viral loads in sacral ganglia were similar for dl5-29 and dl5-29-41L (all p values >0.05). dl5-29 and dl5-29-41L completely protected mice from lethal challenge with HSV-2 and induced virus-specific CD8(+) T cells in the spleens of the animals. Thus, dl5-29 was as immunogenic and protective as dl5-29-41L under these conditions. dl5-29 was at least 250,000-fold less virulent than parental virus by intracranial inoculation in healthy mice, and caused no disease in SCID mice. Both dl5-29-41L and dl5-29 are equally effective and immunogenic in guinea pigs, and dl5-29 is very safe in immunocompromised animals.

The culmination of decades of research on humanized mice is leading to advances in our understanding of human haematopoiesis, innate and adaptive immunity, autoimmunity, infectious diseases, cancer biology and regenerative medicine. In this Review, we discuss the development of these new generations of humanized mice, how they will facilitate translational research in several biomedical disciplines and approaches to overcome the remaining limitations of these models.

Chemokine-driven accumulation of lymphocytes, mononuclear and polymorphonuclear proinflammatory cells in antigenic tissue sites is a key feature of several types of T-cell-dependent autoimmunity and transplant rejection pathology. It is now clear that the immune system expends considerable energy to control this process, exemplified by the sequential layers of regulatory cell input, both innate and adaptive, designed to prevent a classical Type IV or 'delayed-type' hypersensitivity (DTH) reaction from occurring in the visual field of the eye. Yet, despite an abundance of in vitro assays currently available to the human T-cell immunologist, none of them adequately models the human DTH response and its various control features. The theme of this article is that it is relatively easy to model the effector side of the human DTH response with xenogeneic adoptive transfer models. However, we show that in order to detect inhibition of a recall DTH in response to colocalized donor antigen (linked suppression)--a characteristic feature of peripheral tolerance to an organ transplant--both the challenge site and the immunocompetence of the mouse adoptive host are critical factors limiting the sensitivity of the trans-vivo DTH test.

Cryptococcus neoformans (Cn) var. grubii or Cryptococcus neoformans var. neoformans infection is usually associated with immunocompromised hosts, whereas Cryptococcusgattii more frequently causes disease in immunocompetent hosts. We examined the effects of immunodeficiency and glucocorticoid-induced immunosuppression on systemic murine infection induced by i.v. inoculation with these pathogens. SCID and immunocompetent BALB/c and C57BL/6 mice were infected with

Cardiac remodeling in response to pressure overload involves reorganization of the myocytes and extracellular matrix (ECM). Neurohormonal pathways have been described as effector pathways in left ventricular ECM reorganization in response to pressure overload; we now are assessing the role of the T lymphocyte in this process. Mice with defined differences in T-lymphocyte function (C57BL/6 SCID, C57BL/6 WT, and BALB/c) were treated with 50 mg/L of N(G)-nitro-l-arginine methyl ester in their drinking water for 30 days. The immune function of C57BL/6 WT mice was T-helper type 1 (TH1), BALB/c was TH2, and C57BL/6 SCID was null. The arterial blood pressure increased by 30% in all of the strains of mice. However, ventricular stiffness significantly decreased in the C57 SCID, significantly increased in the BALB/c, and did not change in the C57 WT. The characterization of matrix metalloproteinase induction and activation on day 30 was associated with T-lymphocyte function. The total cardiac fibrillar collagen, percentage of fibrillar collagen cross-linking, and the activity of the cross-linking enzyme lysyl oxidase-like-3 (LOXL-3) significantly decreased in the C57 SCID, significantly increased in the BALB/c, and did not change in the C57 WT. This study revealed that the LOXL-3 pathway, namely, gene expression, enzymatic activities, and LOXL-3-mediated collagen cross-linking, was associated with ventricular stiffness and incongruence with lymphocyte function. These data support the concept that the T lymphocytes may play a fundamental regulatory role in cardiac ECM composition through modulation of collagen synthesis, degradation, and cross-linking.

The severe combined immunodeficiency disorder (SCID)-beige/albumin (Alb)-urokinase plasminogen activator (uPA) mouse containing a human-mouse chimeric liver is currently the only small animal model capable of supporting hepatitis C virus (HCV) infection. This model was utilized to characterize the host transcriptional response to HCV infection. The purpose of these studies was to investigate the genetic component of the host response to HCV infection and also to distinguish virus-induced gene expression changes from adaptive HCV-specific immune-mediated effects. Gene expression profiles from HCV-infected mice were also compared to those from HCV-infected patients. Analyses of the gene expression data demonstrate that host factors regulate the response to HCV infection, including the nature of the innate antiviral immune response. They also indicate that HCV mediates gene expression changes, including regulation of lipid metabolism genes, which have the potential to be directly cytopathic, indicating that liver pathology may not be exclusively mediated by HCV-specific adaptive immune responses. This effect appears to be inversely related to the activation of the innate antiviral immune response. In summary, the nature of the initial interferon response to HCV infection may determine the extent of viral-mediated effects on host gene expression.

Differentiated cell types derived from human embryonic stem cells (hESCs) may serve in the future to treat various human diseases. A crucial step toward their successful clinical application is to examine the immune response that might be launched against them after transplantation. We used two experimental platforms to examine the in vivo leukocyte response toward hESCs. First, immunocompetent and immunodeficient mouse strains were used to identify T cells as the major component that causes xenorejection of hESCs. Second, mice that were conditioned to carry peripheral blood leukocytes from human origin were used to test the human leukocyte alloresponse toward undifferentiated and differentiated hESCs. Using this model, we have detected only a minute immune response toward undifferentiated as well as differentiated hESCs over the course of 1 month, although control adult grafts were repeatedly infiltrated with lymphocytes and destroyed. Our data show that the cells evade immune destruction due to a low immunostimulatory potential. Nevertheless, a human cytotoxic T lymphocyte clone that was specifically prepared to recognize two hESC lines could lyse the cells after major histocompatibility complex class I (MHC-I) induction. Although MHC-I levels in hESCs are sufficient for rejection by cytotoxic T cells, our data suggest that the immunostimulatory capacity of the cells is very low. Thus, immunosuppressive regimens for hESC-based therapeutics could be highly reduced compared with conventional organ transplantation because direct allorejection processes of hESCs and their derivatives are considerably weaker.

The quaking(viable) (qkv) mutation, a spontaneous deletion of a multigenic region encompassing roughly 1 Mb at 5.9 cM on the proximal end of mouse chromosome 17, causes severe trembling in all homozygous animals and infertility in all homozygous males. Physiologically, quaking mice exhibit dysmyelination and postmeiotic spermatogenic arrest. Molecular defects in Qkv mice occur in the affected tissues, indicating the primary causes of these pathologies are cell autonomous. However, because both the reproductive and neurological defects are in immune-privileged sites and because some similar pathologies at both sites have been shown to be immune mediated, we tested whether the immune system participates secondarily in manifestation of Qkv phenotypes. The qkv mutation was bred into a severe combined immune-deficient mouse line (SCID; devoid of mature B and T cells) and penetrance of the neurological and the male sterile phenotypes was measured. Results showed that neither defect was ameliorated in the immune-deficient background. We conclude that the Qkv pathologies do not likely involve a B- or T-cell-dependent response against these immune-privileged sites.

Background: The objective of this study was to determine the contribution of commensal bacteria to the innate defense status of gingival tissue by examining the expression of innate host defense mediators in germ-free and conventionally reared groups in both BALBc/ByJ and SCID C.B17 mice., Methods: Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was utilized to determine the constitutive levels within each gingival tissue set (N = 5) for: E-selectin, P-selectin, interleukin-(IL)-8 homologue, tumor necrosis factor-alpha, IL-1beta, intercellular adhesion molecule-(ICAM)-1, ICAM-2, and vascular adhesion molecule-(VCAM)-1. In addition, IL-1beta protein content was determined by enzyme-linked immunosorbent assay (ELISA)., Results: Gingival samples revealed that only IL-1beta mRNA expression among all mediators examined was significantly reduced in conventionally reared mice (P<0.01) compared to germ-free mice. In contrast, IL-1beta protein levels were significantly (P <0.001) higher in conventionally reared mice compared to germ-free animals. Conventionally reared and germ-free SCID C.B17 mice revealed a similar pattern in regard to reduced IL-1beta mRNA and significantly increased IL-1beta protein (P<0.0001)., Conclusion: Commensal microbial colonization influences innate host defense mediator expression of IL-1beta at both the mRNA and protein levels in healthy periodontal tissue in mice.

Here we report the establishment of an in vivo mouse model that allows monitoring of human T cell migration into human skin. This model is based on the use of severe combined immunodeficiency (SCID) mice transplanted with human skin (SCID-hu Skin mice). Adoptively transferred human T helper (Th)2 cells obtained from atopic dermatitis skin lesions or peripheral blood T cells selectively migrate to the human skin grafts of these SCID mice in response to defined chemokines locally injected in the human skin grafts. Homing of human T cells into the human skin on SCID-hu Skin mice is a specific process since it only occurs in response to chemokine ligands that are specific for the chemokine receptors expressed on the migrating T cells. This mechanistic model allows analysis of the relevant steps involved in human T-lymphocyte migration into inflamed skin. In addition, it is successfully used for preclinical testing of drug candidates that are highly selective for human target molecules associated with the different steps of T cell migration in an environment that resembles the physiologic or pathologic conditions occurring in man., (Copyright 2002 Elsevier Science B.V.)

Humans with immune-compromised conditions such as SCID are unable to control infection caused by normally nonpathogenic intracellular pathogens such as Mycobacterium bovis bacillus Calmette-Guérin. We found that SCID beige mice lacking both lymphocytes and NK cells had functionally normal lung macrophages and yet a selectively impaired response of type 1 cytokines IFN-gamma and IL-12, but not TNF-alpha, during M. bovis bacillus Calmette-Guérin infection. These mice succumbed to such infection. A repeated lung gene transfer strategy was designed to reconstitute IFN-gamma in the lung, which allowed investigation of whether adequate activation of innate macrophages could enhance host defense in the complete absence of lymphocytes. IFN-gamma transgene-based treatment was initiated 10 days after the establishment of mycobacterial infection and led to increased levels of both IFN-gamma and IL-12, but not TNF-alpha, in the lung. Lung macrophages were activated to express increased MHC molecules, type 1 cytokines and NO, and increased phagocytic and mycobactericidal activities. Activation of innate immunity markedly inhibited otherwise uncontrollable growth of mycobacteria and prolonged the survival of infected SCID hosts. Thus, our study proposes a cytokine transgene-based therapeutic modality to enhance host defense in immune-compromised hosts against intracellular bacterial infection, and suggests a central effector activity played by IFN-gamma-activated macrophages in antimycobacterial cell-mediated immunity.

We have previously established a model to study the in vivo human IgE response using humanized SCID mice. Allergic SCID mice were obtained following intraperitoneal injection with mononuclear cells from Dermatophagoides pteronyssinus (Dpt)-sensitive patients, and sensitization by Dpt allergen intraperitoneal injection (immunization) or Dpt aerosol (inhalation). Human serum IgE was measured in allergic SCID mice after administration of human recombinant IFN-gamma or the lipopeptide LP 52-71 (derived from peptide p52-71 from Der p 1, Dpt major allergen, coupled to a lipophilic moiety), during the immunization or the inhalation phase. IFN-gamma inhibited human IgE production when given at the time of immunization, but not during inhalation. This effect was long-lasting as Dpt aerosol, given one month after immunization and IFN-gamma administration, failed to increase IgE levels. Unlike Dpt or p52-71, LP 52-71 failed to induce human IgE production at day 14 and 21 after its injection, but did inhibit the development of the IgE response after a secondary Dpt-challenge. Moreover, LP 52-71 administration 14 days after Dpt inhalation decreased IgE levels, in contrast to peptide 52-71, which increased IgE levels. Thus, taken together these results indicate that the development of the human IgE response in allergic SCID mice can be modulated by modified allergen and a Th1 cytokine.

A recent clinical trial of gene therapy for X-linked severe combined immunodeficiency (XSCID) has shown that retroviral-mediated gene correction of bone marrow stem cells can lead to the development of normal immune function. These exciting results have been preceded by successful immune reconstitution in several XSCID mouse models, all carrying null mutations of the common gamma chain (gamma(c)). One question not formally addressed by these previous studies is that of possible dominant-negative effects of the endogenous mutant gamma(c) protein on the activity of the wild-type transferred gene product. The present work was therefore undertaken to study whether corrective gene transfer was applicable to an XSCID murine model with preserved expression of a truncated gammac molecule (Deltagamma(c+)-XSCID). Gene correction of Deltagamma(c+)-XSCID mice resulted in the reconstitution of lymphoid development, and preferential repopulation of lymphoid organs by gene-corrected cells demonstrated the selective advantage of gamma(c)-expressing cells in vivo. Newly developed B cells showed normalization of lipopolysaccharide-mediated proliferation and interleukin-4 (IL-4)-induced immunoglobulin G1 isotype switching. Splenic T cells and thymocytes of treated animals proliferated normally to mitogens and responded to the addition of IL-2, IL-4, and IL-7, indicating functional reconstitution of gammac-sharing receptors. Repopulated thymi showed a clear increase of CD4-/CD8- and CD8+ fractions, both dramatically reduced in untreated Deltagamma(c+)-XSCID mice. These improvements were associated with the restoration of Bcl-2 expression levels and enhanced cell survival. These data indicate that residual expression of the endogenous truncated gamma(c) did not lead to dominant-negative effects in this murine model and suggest that patient selection may not be strictly necessary for gene therapy of XSCID.

The study of megakaryocytopoiesis has been based largely on in vitro assays. We characterize an in vivo model of megakaryocyte and platelet development in which human peripheral blood stem cells (PBSCs) differentiate along megakaryocytic as well as myeloid/lymphoid lineages in sublethally irradiated nonobese diabetic/severe combined immunodeficient (NOD-SCID) mice. Human hematopoiesis preferentially occurs in the bone marrow of the murine recipients, and engraftment is independent of exogenous cytokines. Human colony-forming units-megakaryocyte (CFU-MK) develop predominantly in the bone marrow, and their presence correlates with the overall degree of human cell engraftment. Using a sensitive and specific flow cytometric assay, human platelets are detected in the peripheral blood from weeks 1 to 8 after transplantation. The number of circulating human platelets peaks at week 3 with a mean of 20 x 10(9)/L. These human platelets are functional as assessed by CD62P expression in response to thrombin stimulation in vitro. Exogenous cytokines have a detrimental effect on CFU-MK production after 2 weeks, and animals treated with these cytokines have no circulating platelets 8 weeks after transplantation. Although cytokine stimulation of human PBSCs ex vivo led to a significant increase in CFU-MK, CD34+/41+, and CD41+ cells, these ex vivo expanded cells provided only delayed and transient platelet production in vivo, and no CFU-MK developed in vivo after transplantation. In conclusion, xenogeneic transplantation of human PBSCs into NOD/SCID mice provides an excellent in vivo model to study human megakaryocytopoiesis and platelet production.

Transplantable human hematopoietic stem cells (competitive repopulating units [CRU]) can be quantitated based on their ability to produce large populations of lymphoid and myeloid progeny within 6 weeks in the marrow of intravenously injected, sublethally irradiated NOD/SCID mice. It is shown that the proportions of total injected human fetal liver and cord blood CRU in the marrow of mice 24 hours after transplantation are 5% and 7%, respectively, as determined by limiting-dilution assays in other primary and secondary NOD/SCID mice. The similarity in these 2 seeding efficiency values suggests that mechanisms regulating the ability of human hematopoietic stem cells to enter the marrow from the blood, at least in this xenotransplant model, do not change between fetal life and birth. In addition, it appears that previously reported human stem cell frequencies and their in vivo self-renewal activity measured in NOD/SCID mice have been markedly underestimated. (Blood. 2000;96:3979-3981)

Little is known about the presence, frequency, and in vivo proliferative potential of stromal cells within blood-derived hematopoietic transplants. In this study, nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice were injected with human CD34(+) peripheral blood cells (PBCs) or cord blood cells (CBCs, either enriched for CD34 or density-gradient separated mononuclear cells). Flow cytometric analysis 5 to 11 weeks after transplantation revealed the presence of a human lymphomyeloid hematopoiesis within the murine bone marrow. Immunohistochemical staining of bone marrow cell suspensions using human-specific antibodies showed human cells staining positive for human fibroblast markers, human von Willebrand factor (vWF) and human KDR (vascular endothelial growth factor receptor-2) in mice transplanted with CD34(+) PBCs or CBCs, with mean frequencies between 0.6% and 2.4%. In stromal layers of bone marrow cultures established from the mice, immunohistochemical staining using human-specific antibodies revealed flattened reticular cells or spindle-shaped cells staining positive with human-specific antifibroblast antibodies (mean frequency, 2.2%). Cell populations of more rounded cells stained positive with human-specific antibodies recognizing CD34 (1.5%), vWF (2.2%), and KDR (1.6%). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and subsequent complementary DNA sequencing detected transcripts of human KDR (endothelial specific) and human proline hydroxylase-alpha (fibroblast specific) within the bone marrow and spleen of transplanted mice. Analysis of nontransplanted control mice yielded negative results in immunocytochemistry and RT-PCR. Cells expressing endothelial and fibroblast markers were also detected in the grafts before transplantation, and their numbers increased up to 3 log in vivo after transplantation. These results indicate that stromal progenitor cells are present in human cytokine-mobilized peripheral blood or cord blood that engraft in NOD/SCID mice. (Blood. 2000;96:3971-3978)

Numerous studies indicate that CD4 T cells are required for acute cardiac allograft rejection. However, the precise role for CD4 T cells in this response has remained ambiguous owing to the multipotential properties of this T-cell subpopulation. In the current study, we demonstrate the capacity of CD4 T cells to serve as direct effector cells of cardiac allograft rejection. We show that CD4 T cells are both necessary and sufficient for acute graft rejection, as indicated by adoptive transfer experiments in immune-deficient SCID and rag1(-/-) recipients. We have analyzed the contribution of direct (donor MHC class II restricted) and indirect (host MHC class II restricted) antigen recognition in CD4-mediated rejection. Acute CD4 T cell-mediated rejection required MHC class II expression by the allograft, indicating the importance of direct graft recognition. In contrast, reciprocal experiments indicate that CD4 T cells can acutely reject allogeneic cardiac allografts established in rag1(-/-) hosts that were also MHC class II deficient. This latter result indicates that indirect presentation of donor antigens by host MHC class II is not required for acute CD4-mediated rejection. Taken together, these results indicate that CD4 T cells can serve as effector cells for primary acute cardiac allograft rejection, predominantly via direct donor antigen recognition and independent of indirect reactivity.

C.B-17-SCID/SCID (SCID) mice infected with Angiostrongylus cantonensis yielded a high percentage of worm recovery and did not show any body weight loss until day 24 postinfection. Unexpectedly, C.B-17-+/+(+/+) mice also produced a similar worm burden containing well-developed worms. This is probably attributable to the observation that +/+ mice failed to induce eosinophilia in cerebrospinal fluid (CSF) despite their production of antigen-specific IgA and IgGI; +/+ mice have defective bone-marrow eosinopoiesis, which in turn results in reduced blood and CSF eosinophilia. Interleukin 5 (IL-5) production in +/+ mice is similar to that in BALB/c and C57BL/6 mice. However, bone-marrow eosinopoiesis in response to IL-5 is markedly suppressed in +/+ mice. This is probably associated with impaired expression of common beta-chain mRNA in bone-marrow cells of +/+ mice, which leads to the failure of bone-marrow eosinopoiesis. Hence, +/+ mice may serve as a useful model for the elucidation of eosinophil production in the mouse and for determination of the relationship between parasite infection and the eosinophil.

A Severe Combined Immunodeficient (SCID) mouse model has been established to evaluate experimental conditions leading to the production of factor VIII (FVIII) autoantibodies. To this end, we humanized 10 groups of 7 mice with peripheral blood mononuclear cells of 10 unrelated healthy blood donors (15 x 10(6) cells/mouse). Mice were injected with saline or immunized i.p. with 50 IU of a plasma derived human FVIII 24 h after reconstitution. Further immunization was made with 25 IU of FVIII every fortnight during 6 weeks and animals were sacrificed after 8 weeks. All reconstituted mice showed a spontaneous production of anti-FVIII antibodies in the absence of immunization with the corresponding antigen. However, no differences were observed regarding the quantity or the quality of these antibodies produced in the immunized or the saline group, indicating that tolerance to FVIII had been transferred with cell reconstitution. Affinity purified FVIII specific antibodies were capable of inhibiting FVIII activity and preventing the binding of FVIII to phospholipids in a dose-dependent manner. Immunoprecipitation experiments showed that the antibodies recognized only the C1 and C2 light chain domains. Since antibodies of interest can be found in the SCID mouse model and, moreover, since they are qualitatively comparable with the source donor's antibodies, this model provides a tool to study the regulation of tolerance against self antigens in normal subjects and in acquired haemophilia patients.

Background: Numerous studies have documented antibody responses to nominal antigens in human peripheral blood lymphocyte (hu-PBL)-severe combined immunodeficient (SCID) mice engrafted with PBL. We suggest, therefore, that engraftment of SCID mice by allosensitized cells produces alloreactive antibodies (allo-Ab). As such, SCID mice can be used as a model to examine the cellular basis of the sustenance of humoral alloresponses., Methods: C.B-17 SCID mice were engrafted intraperitoneally with PBL from sensitized uremic patients for 5 weeks and classified into the following: group 1, 8 mice engrafted with unactivated cells (n = 5; n = sensitized patients); group 2, 6 mice engrafted with unactivated PBL (n = 3) followed 2 days later by in vivo activation with interleukin-2 (IL-2) and lipopolysaccharide (LPS); group 3, 11 mice engrafted with cells preactivated in vitro with IL-2 and LPS (n = 6); group 4, 9 mice engrafted with cells preactivated with irradiated allogeneic transformed B cells, IL-2, and LPS (n = 5); group 5, 10 mice engrafted with cells preactivated with IL-2, LPS, and HLA class II allopeptides and adjuvant (n = 6); group 6, 8 control mice engrafted with control cells preactivated with IL-2 and LPS. Two weeks later, each group was rechallenged by the same stimuli. Allo-Ab production was measured by the panel-reactive antibody PRA-STAT ELISA method. Results. Allo-Ab was produced in 54.5% of group 3, 43% of group 4; 80% of group 5, and 0% of groups 1, 2, and 6. The ratio of alloreactive positive wells in the allo-Ab-producing PBL-hu-SCID mice to that present in the respective patient's sera was 82%, 52%, and 87% in groups 3, 4, and 5, respectively. Conclusions. The study demonstrates the feasibility of using the hu-PBL-SCID model to study alloreactive memory B-cell function in humans. Discrete HLA-class allopeptides (group 5) appeared more potent allo-Ab producers than allogeneic cells (group 4).

The past year has brought forth some exciting developments in the use of murine xenotransplantation systems to study the biology and transduction of human hematopoietic stem cells. The effects of cytokines have been studied by injection into the mice or by treatment of the cell inoculum prior to injection. The importance of the cell cycle and integrin expression has been evaluated. New methods of gene therapy have been tested in xenograft models - including cell cycle manipulation and a promising new lentiviral vector system, based on HIV.