Search

A disease affecting guinea pigs called ‘guinea pig lameness’ characterized by clinical signs of depression, lameness of limbs, flaccid paralysis, weight loss and death within a few weeks was first described by Römer in 1911. After a research group in our facility kept laboratory guinea pigs from two different origins together in one room, lameness was observed in two animals. Further investigations revealed a serological immune response against Theiler’s murine encephalomyelitis virus (TMEV; GDVII strain) in these animals. Histopathology of the lumbar spinal cord of these animals showed mononuclear cell infiltration and necrotic neurons in the anterior horn. Therefore, all guinea pigs from this contaminated animal unit, from other units in our facility, as well as from different European institutions and breeding centres were screened for antibodies directed against GDVII. Our investigations showed that approximately 80% of all guinea pigs from the contaminated animal unit were seropositive for GDVII, whereas animals from other separate units were completely negative. In addition, 43% of tested sera from the different European institutions and breeding centres contained antibodies against GDVII. The present data confirm that an unknown viral infection causes an immune response in experimental guinea pigs leading to seroconversion against GDVII and that guinea pigs from a commercial breeder are the source of the infection. [ABSTRACT FROM AUTHOR]

Recent reports suggest that hydrolyzed wheat protein (HWP) variants such as Glupearl® 19S (GP19S) induce immediate-type hypersensitivity via epicutaneous (EC) sensitization. The identification of strong allergens is a key step in product assessment before commercial launch. However, few reports have described the estimation of actual and potential anaphylactic sensitizing capacity. In this study we assessed the strength of both the actual and potential anaphylactic sensitizing capacity by investigating the immediate-type hypersensitivity inducing potential of HWP compared with gluten. We assessed these strengths via the EC route using an EC or intradermal (ID) sensitization method. We quantified the strength of immediate-type hypersensitivity by evaluating the titer of serum antibodies isolated from sensitized subjects using passive cutaneous anaphylaxis (PCA) reactions. We also evaluated the cross-reactivity between GP19S and gluten. GP19S and gluten applied by both the sensitization methods induced obvious IgG1-mediated PCA reactions. GP19S had stronger sensitizing potential than gluten, according to the serum titers and dye spot diameters. The difference in antibody titers between GP19S and gluten was 16-fold for the EC method versus 2-fold for the ID method. GP19S cross-reacted with gluten. Acid hydrolysis of gluten increased anaphylactic sensitizing capacity in the EC method. To our knowledge, our study is the first to quantitatively confirm that HWP and gluten can induce immediate-type hypersensitivity through an intact skin. These findings suggest that acid-HWP imposes a higher risk of EC sensitization than gluten because of the ease with which the former confers a sensitizing effect through the intact skin. [ABSTRACT FROM AUTHOR]

The reduction of brain amyloid beta (Aβ) peptides by anti-Aβ antibodies is one of the possible therapies for Alzheimer's disease. We previously reported that the Aβ peptide vaccine including the T-cell epitope of diphtheria-tetanus combined toxoid (DT) induced anti-Aβ antibodies, and the prior immunization with conventional DT vaccine enhanced the immunogenicity of the peptide. Cynomolgus monkeys were given the peptide vaccine subcutaneously in combination with the prior DT vaccination. Vaccination with a similar regimen was also performed on guinea pigs. The peptide vaccine induced anti-Aβ antibodies in cynomolgus monkeys and guinea pigs without chemical adjuvants, and excessive immune responses were not observed. Those antibodies could preferentially recognize Aβ 40, and Aβ 42 compared to Aβ fibrils. The levels of serum anti-Aβ antibodies and plasma Aβ peptides increased in both animals and decreased the brain Aβ 40 level of guinea pigs. The peptide vaccine could induce a similar binding profile of anti-Aβ antibodies in cynomolgus monkeys and guinea pigs. The peptide vaccination could be expected to reduce the brain Aβ peptides and their toxic effects via clearance of Aβ peptides by generated antibodies. [ABSTRACT FROM AUTHOR]

Abstract: Virus-like particles (VLPs) offer a platform to test the hypothesis that, since antibody binding to native envelope glycoprotein (Env) trimers results in HIV-1 neutralization, that native Env trimers presented in membranes may be useful for inducing neutralizing antibodies (nAbs) in a vaccine setting. So far, VLPs have not fulfilled this potential. Here, using a “shotgun” approach, we evaluated a wide cross-section of variables in a series of VLP immunizations. We identified 3 tentative leads. First, that VLP doses may not have been sufficient for optimal nAb induction. Second, that dampening the antigenicity of non-functional Env (for example uncleaved gp160) using either protease digests or IgG masking may be useful. Third, that guinea pig sera preferentially target non-conserved epitopes and exhibit relatively high background activity, suggesting that rabbits may be preferable as small animal vaccine models. Recent immunogenicity studies in rabbits appear to bear out all 3 of these leads. [Copyright &y& Elsevier]

Abstract: Objective: To develop an effective HIV vaccine strategy that can induce cross-reactive neutralizing antibody. Methods: Codon-optimized gp140 and gp145 env genes derived from HIV-1cn54, a CRF07 B′/C recombinant strain, were constructed as DNA and recombinant Tiantan vaccinia (rTV) vaccines. The effect of heterologous immunization with gp140 and gp145 was tested in mice and guinea pigs. T cell responses were detected using the IFN-γ ELISPOT assay. A panel of primary isolates of clade B′ and B′/C HIV-1 and TZM-bl cells was used to determine the neutralizing activity of immunized sera. Results: The neutralizing antibodies (NAbs) induced by the heterologous immunogen immunization neutralized all HIV-1 B′ and B′/C primary isolates in the guinea pig model. Gp145 and gp140 heterologous prime-boost induced the best neutralizing antibody response with a broad neutralizing spectrum and the highest titer of 1:270 at 6 weeks after the last inoculation. However, the T cell response to HIV-1 peptides was significantly weaker than the gp145+gp145 homologous prime-boost. Conclusions: This heterologous prime-boost immunization strategy could be used to design immunogen-generating broad neutralizing antibodies against genetic variance pathogens. [Copyright &y& Elsevier]

Abstract: Leptospira interrogans serovar Copenhageni causes pulmonary hemorrhages with respiratory failure, a major cause of death in leptospirosis patients. Protective immunity to Leptospira is known to correlate with the production of leptospiral lipopolysaccharide (L-LPS)-specific agglutinating antibodies. We generated L-LPS-specific mouse monoclonal antibodies (MAbs) and investigated if these MAbs can protect guinea pigs against fatal pulmonary hemorrhages caused by serovar Copenhageni. The MAbs L8H4 and L9B11 against 22kDa L-LPS agglutinated leptospires and completely protected guinea pigs from the development of fatal pulmonary hemorrhages by serovar Copenhageni, whereas the MAb L4C1 against 8kDa L-LPS neither agglutinated the bacteria nor protected the animals against the fatal pulmonary hemorrhages. [Copyright &y& Elsevier]

Abstract: To generate monoclonal antibodies to the human ρ1 GABAC receptor, a ligand-gated chloride ion channel that is activated by the neurotransmitter γ-aminobutyric acid (GABA), we recovered the immunoglobulin variable heavy chain (VH) and light chain (VL) regions of a guinea pig immunized with a 14-mer peptide segment of the N-terminal extracellular domain of the ρ1 subunit. Oligonucleotide primers were designed and used to amplify the VH and VL regions of guinea pig RNA by the reverse transcriptase polymerase chain reaction. The amplified and cloned VH and VL regions were transferred together into a phagemid vector, yielding a library of 5×106 members, which displayed chimeric fragments of antigen binding (Fabs) with guinea pig variable and human constant regions fused to protein III of M13 bacteriophage. Through affinity selection of this phage-display library with the biotinylated 14-mer peptide segment of GABAC, we isolated four different antibody fragments that bound specifically to the immunogenic peptide. Phage particles displaying two of these antibodies, but not negative controls, bound selectively to the surface of neuroblastoma cells expressing the ρ1 GABAC receptor. Such antibody fragments will be useful in future studies involving targeting of specific neural tissues that express the GABAC receptor. [Copyright &y& Elsevier]

Several conserved neutralizing epitopes have been identified in the HIV Env protein and among these, the MPER of gp41 has received great attention and is widely recognized as a promising target. However, little success has been achieved in eliciting MPER-specific HIV neutralizing antibodies by a number of different vaccine strategies. We investigated the ability of HA/gp41 chimeric protein-based vaccines, which were designed to enhance the exposure of the MPER in its native conformation, to induce MPER-specific HIV neutralizing antibodies. In characterization of the HA/gp41 chimeric protein, we found that by mutating an unpaired Cys residue (Cys-14) in its HA1 subunit to a Ser residue, the modified chimeric protein HA-C14S/gp41 showed increased reactivity to a conformation-sensitive monoclonal antibody against HA and formed more stable trimers in VLPs. On the other hand, HA-C14S/gp41 and HA/gp41 chimeric proteins expressed on the cell surfaces exhibited similar reactivity to monoclonal antibodies 2F5 and 4E10. Immunization of guinea pigs using the HA-C14S/gp41 DNA or VLP vaccines induced antibodies against the HIV gp41 as well as to a peptide corresponding to a segment of MPER at higher levels than immunization by standard HIV VLPs. Further, sera from vaccinated guinea pigs were found to exhibit HIV neutralizing activities. Moreover, sera from guinea pigs vaccinated by HA-C14S/gp41 DNA and VLP vaccines but not the standard HIV VLPs, were found to neutralize HIV pseudovirions containing a SIV-4E10 chimeric Env protein. The virus neutralization could be blocked by a MPER-specific peptide, thus demonstrating induction of MPER-specific HIV neutralizing antibodies by this novel vaccine strategy. These results show that induction of MPER-specific HIV neutralizing antibodies can be achieved through a rationally designed vaccine strategy. [ABSTRACT FROM AUTHOR]

Abstract: The basis for efficacy of the recombinant botulinum vaccine, serotypes A and B (rBV A/B) is that neutralizing antibodies induced by vaccination bind to botulinum neurotoxin complex serotype A, subtype A1 (BoNT/A1) and serotype B, subtype B1 (BoNT/B1) and prevent their actions at cholinergic neurons. The protective capacity of BoNT/A1 and BoNT/B1 neutralizing antibodies derived from the serum of clinical volunteers vaccinated with rBV A/B was evaluated in a guinea pig passive transfer model and a mouse bioassay. Guinea pigs passively immunized to achieve circulating neutralizing antibody concentration (NAC) levels representing the lowest measurable concentrations for BoNT/A1 and BoNT/B1 were protected against an intramuscular (IM) challenge more than 10 times the guinea pig IM median lethal dosage for BoNT/A1 and BoNT/B1. The passively immunized guinea pigs were asymptomatic during the 14-day post-challenge observation period. Control guinea pigs died within 48h after challenge. Calculation of neutralizing efficiency of antibodies using results from a mouse bioassay indicated that a simple linearly proportional relationship does not exist between NAC level and the amount of BoNT neutralized. Based on this finding, estimates of level of protection must consider variability in BoNT neutralizing efficiency at different NAC levels. The protective capacity of human BoNT/A1 and BoNT/B1 neutralizing antibodies induced by rBV A/B vaccination was verified in a guinea pig passive immunization model. Additionally, estimates of the neutralizing efficiency have been established for BoNT/A1 and BoNT/B1 neutralizing antibodies obtained from clinical volunteers vaccinated with the rBV A/B. [ABSTRACT FROM AUTHOR]

The native envelope (Env) spike on the surface of human immunodeficiency virus type 1 (HIV-1) is trimeric, and thus trimeric Env vaccine immunogens are currently being explored in preclinical immunogenicity studies. Key challenges have included the production and purification of biochemically homogeneous and stable trimers and the evaluation of these immunogens utilizing standardized virus panels for neutralization assays. Here we report the binding and neutralizing antibody (NAb) responses elicited by clade A (92UG037.8) and clade C (CZA97.012) Env gp140 trimer immunogens in guinea pigs. These trimers have been selected and engineered for optimal biochemical stability and have defined antigenic properties. Purified gp140 trimers with Ribi adjuvant elicited potent, cross-clade NAb responses against tier 1 viruses as well as detectable but low-titer NAb responses against select tier 2 viruses from clades A, B, and C. In particular, the clade C trimer elicited NAbs that neutralized 27%, 20%, and 47% of tier 2 viruses from clades A, B, and C, respectively. Heterologous DNA prime, protein boost as well as DNA prime, recombinant adenovirus boost regimens expressing these antigens, however, did not result in an increased magnitude or breadth of NAb responses in this system. These data demonstrate the immunogenicity of stable, homogeneous clade A and clade C gp140 trimers and exemplify the utility of standardized tier 1 and tier 2 virus panels for assessing the NAb responses of candidate HIV-1 Env immunogens. [ABSTRACT FROM AUTHOR]

The article presents a study which serologically investigates the prevalence of antibodies against enteroviruses in brushtail possums (Trichosurus vulpecula) in New Zealand. The study used Enzyme-Linked Immunosorbent Assay to detect enterovirus antibodies, and the use of guinea-pig Immunoglobulin G (IgG) fractions as capture antibodies. It reveals that enterovirus distribution is restricted to regions where they are originally isolated due to natural population barriers, such as rivers.

Abstract: We investigated the neurochemical characteristics of olfactory ensheathing cells (OECs) in adult cats and in adult guinea pigs. Three conventional biomarkers for OECs, p75 neurotrophin receptor (p75NTR), S100, and glial fibrillary acidic protein (GFAP), as well as two recently identified biomarkers, smooth muscle α-actin (SMA) and calponin, were used. We found that 1) antibodies against SMA and S100 yielded positive immunostaining of mucosal and bulbar OECs in cats and guinea pigs; 2) antibodies against GFAP gave positive immunostaining of mucosal and bulbar OECs in cats; and 3) antibodies against calponin yielded positive immunostaining of bulbar OECs in adult cats. Unexpectedly, antibodies against p75NTR failed to positively stain mucosal and bulbar OECs in cats and guinea pigs, and antibodies against GFAP and calponin failed to positively stain mucosal and bulbar OECs in guinea pigs. These findings show the importance for empirical testing of all biomarkers for OECs among different mammalian species when attempting to identify these cells in vivo, in vitro, and following intraspinal implantation. [Copyright &y& Elsevier]

Abstract: We isolated and identified six subgenogroups (B2, B4, B5, C1, C2, and C4) of enterovirus 71 (EV71) between 1990 and 2007 in Yamagata, Japan. We measured neutralizing antibody (NT Ab) titers against those subgenogroup strains and the BrCr reference strain for antigenic analysis. Serological analysis of 83 residents in Yamagata in 2004 showed that differences in the NT Ab titer of each individual against the different subgenogroups were mostly within 4-fold. Furthermore, sera from guinea pigs, immunized with the B2 and C1 strains indicated cross-antigenicity among the seven different subgenogroups. In conclusion, our results showed that cross-antigenicity exists among EV71 strains from different subgenogroups circulating in the community through genomic evolution. Our results also suggest that eliciting neutralizing antibodies against one genotype is likely to confer cross-neutralization against other genotypes. [Copyright &y& Elsevier]

Abstract: Previously, treatment with anti-gpTNFα antibody enhanced TNFα mRNA expression in pulmonary granulomas microdissected from non-vaccinated guinea pigs, and modified splenic granuloma architecture. In this study, pleural fluid, cells, and granulomatous tissues were collected 3, 5, and 8days post-pleurisy induction in guinea pigs treated with anti-gpTNFα or normal serum control. Neutralizing TNFα reduced the percentage of macrophages in the pleural exudate while increasing the proportions of neutrophils and lymphocytes. Cell-associated mycobacterial loads were increased in guinea pigs treated with anti-gpTNFα antibody. Cells from the pleural exudate in both treatment groups at day 3 expressed predominantly TNFα and IFNγ mRNA. By day 5, treatment with anti-gpTNFα antibody significantly reduced TNFα mRNA and increased TGFβ and iNOS mRNA expression, a transition which did not occur in the control group until day 8. TNFα mRNA overwhelmed the cytokine milieu of microdissected pleural granulomas in the control group at day 3 whereas TNFα, IFNγ, and TGFβ mRNA dominated the anti-gpTNFα-treated group. At day 8, granulomas from the control group began shifting towards an anti-inflammatory profile with increased levels of TGFβ mRNA. Neutralization of TNFα hastened the transition to an anti-inflammatory cytokine response in guinea pig pleural granulomas and exudate cells. [Copyright &y& Elsevier]

A new sonogenerated chemiluminescence (SCL) system has been developed to investigate the SCL behavior of acidinium ester (AE). The optimum parameters for this SCL system have also been investigated in detail. Under the optimum conditions, a typical SCL signal could be obtained in a mixture of DMF and alkaline water solutions with volume ratio of 3 : 2. According to electrospray ionization mass spectrometry and sonochemiluminescence emission spectra, SCL emission could be ascribed to the formation of N-methylacridone with a different mechanism from that in both the chemiluminescence and electrochemiluminescence reaction of acridinium ester. The acridinium ester has been used as a SCL probe for labeling of anti-human insulin guinea pig polyclonal antibody, and it was found that the concentration of AE-conjugated antibody was linear with the SCL intensity in the range of 0.15–0.75 ppb with a linear correlation coefficient of 0.9980. [ABSTRACT FROM AUTHOR]

Abstract: Placental growth dynamics are an important, but poorly understood aspect of placentation for which suitable animal models are lacking. Although the guinea pig is recognised as a valuable model for human pregnancy, its suitability for this purpose is not apparent, since the developmental and evolutionary processes that led to its lobulated placenta are not fully understood. Therefore, a study on immunohistochemistry has been undertaken, including the antibody mib-1 against protein Ki-67 as a proliferation marker. It was found that cellular trophoblast derived from the placental margin is the major centre of proliferation, supported by a moderate number of proliferating cells inside the labyrinth. In contrast to the ancestral condition of caviomorph rodents, the evolution of significant placental lobulation requires the latter source of proliferation. The distribution pattern of proliferating trophoblast cells revealed for the guinea pig strongly resembles the distribution in the human placenta in that (a) evenly distributed, moderate numbers of cells occur within the exchange area and (b) focal accumulations of proliferating trophoblast cells are present along the fetal mesenchymal border and appear to serve as a growth zone for appositional growth of new exchange tissues. Thus, the guinea pig appears to be an appropriate animal model for placental growth processes in human pregnancies. [Copyright &y& Elsevier]

To express human papillomavirus (HPV) L1 capsid protein in the recombinant strain of Shigella and study the potential of a live attenuated Shigella-based HPV prophylactic vaccine in preventing HPV infection, the icsA/virG fragment of Shigella-based prokaryotic expression plasmid pHS3199 was constructed. HPV type 16 L1 (HPV16L1) gene was inserted into plasmid pHS3199 to form the pHS3199-HPV16L1 construct, and pHS3199-HPV16L1 was electroporated into a live attenuated Shigella strain sh42. Western blotting analysis showed that HPV16L1 could be expressed stably in the recombinant strain sh42-HPV16L1. Sereny test results were negative, which showed that the sh42-HPV16L1 lost virulence. However, the attenuated recombinant strain partially maintained the invasive property as indicated by the HeLa cell infection assay. Specific IgG, IgA antibody against HPV16L1 virus-like particles (VLPs) were detected in the sera, intestinal lavage and vaginal lavage from animals immunized by sh42-HPV16L1. The number of antibody-secreting cells in the spleen and draining lymph nodes were increased significantly compared with the control group. Sera from immunized animals inhibited murine hemagglutination induced by HPV16L1 VLPs, which indicated that the candidate vaccine could stimulate an efficient immune response in guinea pig's mucosal sites. This may be an effective strategy for the development of an HPV prophylactic oral vaccine. Edited by Guang-Di LI [ABSTRACT FROM AUTHOR]

The pathogenicity of five black-pigmented strains of Bacteroides was tested in subcutaneously implanted Teflon cages in guinea pigs. The tissue reaction around the cages was registered and the contents of the fluid of the cages were analyzed. Two strains of B. intermedius produced a localized abscess around the cages, while one strain (381) of B. gingivalis and an asaccharolytic strain (BN11a-f) different from B. gingivalis did not induce any signs of abscess formation. One strain (W83) of B. gingivalis caused extensive purulent breakdown of the tissues. When the inoculum of strain W83 contained more than 109 cells, the animals were killed. Strain W83 was the only strain that increased in number in the cage. The fluid of cages inoculated with strain W83 was also remarkably different from the fluid of cages inoculated with the other strains. The fluid had a high proteolytic activity. No C3 protein of complement and only traces of immunoglobulins could be detected in the fluid. Both strain W83 and strain 381 had a high proteolytic activity against whole guinea-pig serum and when bacteria of these two strains were incubated with guinea-pig serum for 24 h, almost all serum proteins, including the C3 protein, were degraded. These two strains might thus have similar capacity in perturbing the host defence when inoculated into the tissue cages. The actual difference in pathogenicity between the strains might be explained by a recent finding that the pathogenic strain W83, but not strain 381, requires complement in activating polymorphonuclear leukocytes. The degradation of the C3 protein by the pathogenic strain W83 of B. gingivalis thus may be the crucial event in its perturbation of the host defence. A degradation of the C3 protein by strain 381 would be of no help in eluding the host defence, since this strain activates polymorphonuclear leukocytes in the absence of complement. [ABSTRACT FROM AUTHOR]

The cross-reaction of antibodies to tubular basement membrane (TBM) with alveolar basement membrane (ABM) has been studied in guinea-pigs with tubulointerstitial (TI) nephritis. Fortythree of fifty-two Hartley guinea-pigs immunized with rabbit TBM in complete Freund's adjuvant developed TI nephritis. In addition to linear deposits of guinea-pig IgG and C3 in the TBM, thirty-two of the nephritic animals showed linear immune deposits in ABM; twelve of these animals had thickened alveolar septa and increased numbers of polymorphonuclear (PMN) leucocytes in lung tissue. Sera and eluates of kidney and lung from nephritic guinea-pigs reacted strongly with TBM and more weakly with ABM of normal animals. Absorption experiments suggested that antibodies to TBM and ABM were closely related or identical. Only a minority of guinea pigs immunized with TBM showed in vivo binding of IgG to glomerular basement membrane (GBM). Immunization of guinea-pigs with lung-homogenate-induced antibodies binding to TBM and ABM (in approximately 45% of animals) and to GBM (in approximately 30% of animals). Immunization with crude GBM-induced antibodies which reacted preferentially with TBM and ABM. In contrast, collagenase-treated GBM-induced antibodies preferentially reactive with GBM. TI nephritis was induced in both Strain 13 and Strain 2 guinea-pigs, but the nephropathy developed much faster in Strain 13 animals. Immunization with rabbit TBM-induced antibodies reactive with ABM in 25% of Strain 13 guinea-pigs and in 50% of Strain 2 guinea-pigs, respectively. [ABSTRACT FROM AUTHOR]

A competitive radiobloassay method for soluble immune complexes in sera has been used to study sera from patients with rheumatoid arthritis. Twenty-eight out of sixty-two sera from selected seropositive rheumatoid patients were found to produce enhanced uptake of radio-iodinated human aggregated IgG by guinea- pig macrophages in contrast with the inhibition of uptake seen with SLE sera. Twenty-two out of the twenty-eight enhancing sera belonged to patients with cutaneous vasculitis. None of the twenty-two sera from seronegative rheumatoid patients possessed enhancing properties and none of these patients had clinical evidence of vasculitis. Three patients with seropositive SLE had sera with enhancing properties and had cutaneous vasculitis. We have shown that the enhancement is probably due to the presence in sera of immune complexes or altered lgG bound to rheumatoid factor. The possible mechanism has been investigated and it appears that there is increased binding of radio-iodinated aggregated IgG to free valencies on rheumatoid factor already bound to immune complexes. [ABSTRACT FROM AUTHOR]

Purfied mouse immunoglobulins with specific activity against Mycoplasma pulmonis were examined for their ability to protect mice against intranasal (i.n.) infection with this organism. The survival of mycoplasmas in the respiratory tract of mice inoculated i.n. with M. pulmonis mixed with either IgG1, IgG2a. lgG2b or IgA antibodies was less than that seen in control animals inoculated with mycoplasmas mixed with normal mouse serum. The ways in which the immunoglobulin fractions could have mediated resistance were examined in vitro. IgG1, lgG2a and lgG2b antibody fractions killed M. pulmonis in the presence of guinea-pig complement, and also promoted the phagocytosis of M. pulmonis by mouse lung macrophages. In contrast, IgA antibody did not appear to be either mycoplasmacidal or opsonic. [ABSTRACT FROM AUTHOR]

The role of complement in the processing of soluble immune aggregates by guinea-pig peritoneal macrophages was studied in a homologous system in vitro. Stable soluble aggregates of guinea-pig IgG1 are shown to activate the alternative pathway in C4-deficient guinea-pig serum. At 37' and under serum-free conditions, adherent peritoneal macrophages degraded in 2 hr at least 50% of the available immunoglobulin aggregates. Addition of fresh C4D serum to the incubation mixtures caused a two-fold increase in the rate of degradation. The stimulating effect of C4D serum was complement-mediated, because it was abolished by heat treatment, CoVF treatment and specific C3 depletion of the C4D serum. Functional inactivation of C3 receptors on the macro- phages by trypsin also impeded the stimulating effect of fresh C4D serum. The results indicate that the alternative pathway of complement contributes significantly to the elimination of soluble immune complexes by mononuclear phagocytes. [ABSTRACT FROM AUTHOR]

The cells of the B lymphocytic leukaemia (L2C) of strain 2 guinea-pigs have IgM on their surfaces but produce insufficient monoclonal IgM in vivo to be detectable by conventional serum electrophoresis. A radioimmunoassay, using anti-idiotypic antibody raised against the surface IgM of these cells, has been used to estimate levels of extracellular IgM produced both in vitro and in vivo. Analyses of the contributions to such IgM from the cell surface and from an export pathway have been made by examining the effect of prior removal of surface Fabµ by papain, and by following the fate of radio-iodinated surface IgM. Results suggest that the extracellular IgM arises predominantly from an export pathway, being exported in both pentameric and monomeric forms. Only a minute contribution, possibly in the form of vesicle-bound monomeric IgM, appears to derive from the cell surface. Radioimmunoassay was used to monitor the increasing levels of this leukaemic cell product during the course of the disease. Idiotypic IgM was detectable when the body load of neoplastic cells was approximately 4% of that detectable by an increased white cell count in the blood. [ABSTRACT FROM AUTHOR]

Experimental allergic encephalitis (EAE) was suppressed in guinea-pigs that had been sensitized with 50 μg of bovine myelin basic protein (MyBP) in Freund's complete adjuvant (FCA) by daily injections of 500 μg of the bovine spinal cord protein (BSCP) in saline between day 8 (D 8) and D 23 after sensitization. Injections of 500 μg of bovine serum albumin in saline, or saline alone, did not suppress disease. Reversal of clinical disease was achieved with doses of 750 μg of BSCP in saline when treatment was begun within a day after the first sign of disease was observed. Six injections of 500 μg of BSCP in Freund's incomplete adjuvant (FIA) were required to suppress EAE whether BSCP-FIA injections were begun on D 0 or as late as D 8 when T cells sensitized to MyBP had invaded the central nervous system. When administration of BSCP-FIA was withheld until after disease onset, only three or four injections were needed to reverse clinical signs. BSCP appeared to be as effective quantitatively as MyBP in the suppression or treatment of disease. Because there is no cross-reaction between BSCP and MyBP at the antibody level, the present results raise the possibility that the suppressive activity of BSCP may be due to an amino acid sequence in BSCP and MyBP that is recognized only by T cells. When antigens were injected in FIA at 4 day intervals after sensitization, the onset of disease was delayed up to 5 days. Moreover, even bovine gammaglobulin appeared to have suppressive activity when injected three or four times in FIA. The findings suggest that assessments of the suppressive capacity of an antigen may be inaccurate if the antigen is injected in FIA frequently during the interval between sensitization and onset of disease. [ABSTRACT FROM AUTHOR]

This study examined the mechanisms of E-rosette formation of mitogen-stimulated canine peripheral blood lymphocytes with human and guinea-pig erythrocytes (E). In vitro culture with phytohaemagglutinin-P (PHA-P) increased the number of E-rosette forming cells two- to three-fold within 1 h and ten-fold by 48 h. Mitogen-enhancement of 1 h rosettes occurred via cross-linking of E to lymphocytes by PHA-P. Forty-eight hour rosettes, mediated by natural cytophilic antibodies in serum, resulted from PHA-P-induced increases in the number of cellular Fc receptors for this immunoglobulin. The data obtained in this study indicate that E-rosette formation by resting or mitogen-stimulated canine lymphocytes is neither a reliable nor a specific T-cell marker in this species. [ABSTRACT FROM AUTHOR]

Cellular localization of 2,4-dinitrophenyl (DNP) groups in the peripheral lymphoid system of guinea-pigs was studied at various times after painting the skin with 2,4-dinitrochlorobenzene (DNCB) by the immunofluorescent method using anti-DNP anti- body. The cells taking up the stain (DNP cells) were shown to be mainly lymphocytes. At 1-6 h after painting the majority of DNP cells were found in the peripheral blood and the spleen but the maximum number was reached in the lymph node draining the site of DNCB application 12 h after painting. Injecting cyclophosphamide (CY) 3 days before painting with DNCB, heightened the number of DNP cells residing in the draining node. The animals treated with the tolerogen, 2,4-dinitrobenzene sulphonic acid sodium salt (DNBSO3Na), and then painted with DNCB, had fewer DNP cells than those animals which had simply been painted once with DNCB. The culture supernatants prepared from the draining nodes of both normal and tolerant animals partially blocked the anti-DNP antibody binding with DNP cells. It is suggested that the cells associated with DNP groups residing in the draining lymph node act as immunogens in the immunizing process of contact sensitivity. [ABSTRACT FROM AUTHOR]

The cytophilic binding of immune complexes by peritoneal exudate cells (PEC) from adjuvant-stimulated guinea-pigs was studied using 125I-labelled guinea-pig IgGl, IgG2 and 1gM anti-bodies to the dinitrophenyl (DNP) group. The influence of hapten density upon cytophilic activity was studied by the addition of DNP-conjugated antigens to antibody in 2-200 molar ratios of DNP : antibody. Only IgG2 binding was enhanced by immune complex formation, and the increased binding of IgG2 anti-DNP was dependent on the number of DNP determinants per antigen molecule. Cytophilic activity with ϵ-DNP-L-lysine (DNP-LYS), αϵ-di-DNP-L-Iysine (DNP-LYS-DNP), or DNP1-8-BSA was no greater than that seen in the absence of hapten. Increased cytophilic binding was noted only with DNP20-41-BSA. The binding of IgG2 and IgG2 anti-DNP : DNP-bovine serum albumin (BSA) complexes was inhibited by monomeric IgG2. The relative cytophilic capacities of guinea-pig immunoglobulins appeared as follows: IgG2>IgG1>1gM. IgG1 and IgM binding of DNP conjugates did not enhance their cytophilic activity; therefore, IgG1 and IgM cytophilic binding to PEC was considered biologically insignificant. This investigation provides further evidence that cytophilic binding of immune complexes to macrophages is due to the co-operative action of multiple Fc sites rather than a conformational change in the IgG2 antibodies, and serum proteins, notably complement components, can alter the binding and/or phagocytosis of IgG2 anti-DNP: DNP-BSA complexes. [ABSTRACT FROM AUTHOR]

The synthetic antigen denoted P2-A-L, comprising the fragment P2 of the coat protein of MS-2 coliphage attached to multichain poly-DLalanine, served for the immunization of guinea-pigs. Immunization was carried out either in phosphate buffered saline (PBS) or in Freund's incomplete adjuvant (FIA) in the presence or absence of a small molecular weight peptidoglycan prepared from Bacillus megaterium, which was checked for its adjuvant effect. The various antisera were assessed by their capacity to neutralize MS-2 bacteriophage viability. When injected in PBS or FIA, P2-A--L did not elicit any measurable anti-phage activity. Addition of the peptidoglycan by simple mixing did not bring about a significant increase in antibody production. However, when the peptidoglycan was chemically linked to the P2-A--L conjugate, it had a marked adjuvant effect when the material was administered in FIA, almost identical to the extent of the effect of Freund's complete adjuvant. [ABSTRACT FROM AUTHOR]

When 2,4-dinitrophenylated cells (DNP-E. coli) and lipopolysaccharides (DNP-LPS) of Escherichia coli were injected i.p. into guinea-pigs, they were capable of inducing sequential production of IgM and IgG2 anti-DNP antibodies, both of which were substantially thymus-independent, but only a trace of IgG1 anti-DNP antibody was produced. On the other hand, thymus-dependent DNP-bovine serum albumin (DNP-BSA) induced concomitantly both the IgG1 and IgG2 antibody responses in the presence of LPS. Therefore, the preferential IgG2 antibody response against DNP-LPS seems to be elicited with DNP-LPS itself and not by a combination of mitogenic stimulation with LPS and haptenic stimulation with other contaminating substances carrying DNP residues. Furthermore, it may not be related to affinity of the antibodies produced since there was no significant difference in the affinity for DNP residue between the IgG2 and IgG1 anti-DNP antibodies produced with DNP-E. coli and DNP-BSA, respectively. [ABSTRACT FROM AUTHOR]

The ability of guinea-pig spleen and lymph node cells to undergo a proliferative response in vitro in the presence of mitogens (concanavalin A and lipopolysaccharide), a specific antigen (oxidized ferredoxin), and allogeneic cells was assessed under a variety of conditions. Time and dose dependency of the responses was measured in RPMI 1640, RPMI 1640 plus mercaptoethanol (ME), RPMI 1640 plus foetal calf serum (FCS), and RPMI 1640 with ME and FCS. Mitogen responses were also measured after treatment of the cells with sheep anti-guinea pig immunoglobulin (SaGPIg) and complement (C') or after passage through nylon wool columns. Lipopolysaccharide (LPS) stimulated the cells under all media conditions over a wide range of concentrations but over a narrow time period. Nylon wool treatment of the cells eliminated the LPS response while SaGPIg and C' reduced it. Concanavalin A (con A) stimulated the cells under all test conditions and demonstrated a dose-time interrelationship in terms of maximum response. Pre-treatment of cells with SaGPIg and C' enhanced the response to con A while nylon wool fractionation diminished it somewhat. Only lymph node cells responded in vitro to oxidized ferredoxin (OFd). In serum-free media the OFd responses were maximal at 48 hours whereas in media containing FCS proliferative responses were supported for a prolonged period and appeared to be bimodal. Except for an early response with RPMI 1640 and ME, only media containing FCS supported stimulation in the mixed leucocyte culture. [ABSTRACT FROM AUTHOR]

Anti-rat lymphocyte serum was raised in guinea-pigs in order to study the ability of two 7S immunoglobulin classes to prolong the survival of rat skin homografts. Both classes, complement-fixing IgG2 and anaphylactic IgG1 are active, although the threshold for IgG2 activity is higher. This threshold can be lowered w hen a mixture of both classes is used Thus, in this system, complement activation is not a requisite, and different mechanisms must come into play according to the class of anti-lymphocyte antibodies used Moreover, these results have bearings on the postulated regulatory function of IgG1-antigen complexes [ABSTRACT FROM AUTHOR]

The effect of antigenic competition on antibody affinity was studied using a haptenic system in guinea-pigs. A moderate depression in the amount of antibody formed, as a result of antigenic competition, had relatively little effect on affinity. Increasing the dose of the competing antigen resulted in a greater degree of competition. Under these conditions a large amount of low affinity antibody was produced by the animals while essentially no high affinity antibody was detectable. Thus, marked competition appeared to result in a failure to select for high affinity antibody synthesis. [ABSTRACT FROM AUTHOR]

Uncoupled peptides from all seven serotypes of foot-and-mouth disease virus (FMDV) protein VPI have been used to elicit neutralizing antibody responses in guinea-pigs. The responses were largely serotype specific, although some significant cross-neutralization was observed. Dimeric tandem peptides have also been used to simultaneously elicit neutralizing antibodies to two different FMDV serotypes. The possible existence of structural features common to the B-cell neutralization sites or the guinea-pig helper T-cell sites within all seven peptides are analysed and discussed. [ABSTRACT FROM AUTHOR]

This study addresses macrophage activation in guinea-pigs vaccinated with radiation-attenuated cercariae of Schistosom mansoni. Peritoneal exudate macrophages elicited in vaccinated animals by mineral oil injection were activated to kill larval schistosomes in vitro. Killing efficiency is dependent upon the cell : target ratio employed and is enhanced by, but is not strictly dependent on, the presence of specific antibodies. Macrophages co-cultured with parasites release superoxide radicals and hydrogen peroxide, but the use of inhibitors has shown that neither of these reactive oxygen intermediates are the causal agents of cellular cytotoxicity in this system. Oil-elicited macrophages from naive guinea-pigs do not show comparable activation; they can, however, be activated in vitro by incubation with culture supernatant fluids from schistosome antigen-stimulated spleen, or lymph node cells harvested from vaccinated guinea-pigs. Naive macrophages activated in this way kill schistosomula in vitro and release the activation markers IL-1 and superoxide anion. The macrophage-activating factor (MAF) present in spleen cell culture supernatant fluids has a MW of 35,000-55,000, but does not have the chemical characteristics of gamma-interferon. In this study MAE is shown to be released by a population of lymph node cells that does not adhere to nylon-wool columns, that responds well in proliferation assays to schistosome antigens and to the T-cell mitogen concanavalin A, but does not respond to the B-cell mitogen lipopolysaccharide. These cells have been identified as small lymphocytes. [ABSTRACT FROM AUTHOR]

Uncoupled synthetic peptide representing the sequence of amino acids 141–160 of foot-and-mouth disease virus (FMDV) protein VP1 induced a virus-neutralizing antibody response in guinea-pigs. This response required incomplete Freund's adjuvant (IFA) for the primary inoculation and was dependent on the presence of an added cysteine residue with an unblocked sulphydryl group at the carboxy-terminus. Secondary immunization could be carried out in the absence of adjuvant. A study of the relative activities of nested sets of uncoupled peptides from 150–160 to 135–160 and 141–160 to 141–155 indicated that amino acids 146–156 were critical for the induction of virus-neutralizing antibodies and that extension to 137–160 further improved this response. Results of in vitro proliferation studies demonstrated that the carboxy-terminal residues on this peptide may form a T- cell epitope. The significance of these observations in the broader context of synthetic peptide vaccines is discussed. [ABSTRACT FROM AUTHOR]

Dermal-epidermal separation (DES) could be produced in vivo, 6 h after the injection of sera taken from patients with bullous pemphigoid into the dorsal skin of Hartley guinea pigs. DES did not occur when antihuman IgG rabbit serum was injected prior to the injection of the sera taken from patients with bullous pemphigoid. When IgG fraction from the patient's sera was injected, DES was also observed. Histologic findings in the skin specimens in vivo with concentrated sera or IgG fraction have shown DES, some cell infiltrations of neutrophils. eosinophils, and some lymphocytes similar to the skin Lesions of bullous pemphigoid patients. Various reagents, such as colchicine, cytochalasin B. EDTA. and steroid were injected prior to the IgG fraction injection. DES and the migration of polymorphonuclear (PMN) leukocytes were inhibited by the preinjection of these reagents. These observations suggest that the migration of PMN leukocytes was necessary for the formation of DES. When IgG fraction was injected into C3-inactivated guinea pigs with cobra venom factor, DES was inhibited, whereas DES was not completely inhibited when IgG fraction was injected into C4-deficient guinea pigs. These results suggested that an alternative pathway may be necessary for DES. [ABSTRACT FROM AUTHOR]

Delayed-type hypersensitivity against staphylococcal antigens was induced in guinea pigs using Freund's incomplete as well as Freund's complete adjuvant. In animals sensitized with Freund's complete adjuvant the induction time and the duration of delayed-type hypersensitivity were longer and the skin reactions were stronger compared to animals sensitized with Freund's incomplete adjuvant. The difference between animals sensitized with Freund's incomplete or complete adjuvant may reflect the difference between tuberculin- and Jones-Mote type hypersensitivity. [ABSTRACT FROM AUTHOR]

We have examined the immunological activity of five affinity-purified protein antigens from Mycobacterium tuberculosis in seven inbred and one outbred guinea pig strains. The test systems were measurements of delayed-type hypersensitivity (Dth) responses, lymphocyte stimulation assays (LS), and antibody response measurements. The results showed significant differences in the immunogenicity of the single-protein antigens and, when the antigens were considered separately, highly significant guinea pig strain differences. The outbred guinea pig strain behaved as a Dth high responder to all antigens studied. The order of magnitude of the Dth responses was not usually correlated with that of the corresponding antibody responses for the individual guinea pig strain-antigen combinations. In particular, when compared with the other strains, strain 2 guinea pigs generally gave the lowest Dth, but the highest antibody responses. A 38,000 molecular weight protein, possessing M. tuberculosis complex-specific B-cell determinants, appeared immunodominant in 5 out of 7 strains. Our Dth data in the inbred strains further suggest the presence of an M. tuberculosis-specific T-cell epitope. A T-cell line, 11D9, derived from the high-responder guinea pig strain 13 reactive to this protein, was shown to be able to confer a tuberculin-like skin reaction in vivo. LS assays with recombinant 38-kDa protein and truncated versions of the protein mapped the 11D9-defined T-cell epitope to the middle part of the molecule. [ABSTRACT FROM AUTHOR]

Inbred guinea pigs selected for high (IMM/S) respectively low (IMM/R) responsiveness to ovalbumin (OA) as measured by induced respiratory anaphylaxis, were investigated for atopic immune responses of their conjunctival mucosa. IMM/S animals sensitized either by inhalation of OA, or by instillation of antigen into the conjunctival sac, developed regularly an acute ocular inflammatory response to topical (conjunctival) challenge with the allergen. A minimum of 1 μg OA dropped repeatedly into the conjunctival sac was enough for both ocular and systemic sensitization of the animals, but the minimal dose of effective challenge was considerably higher. In IMM/R animals, ocular hypersensitivity was not achieved by inhalation of OA, but after topical administration of the antigen some of the IMM/R strains could be challenged to ocular anaphylactic responses of the same intensity as observed in IMM/S animals. The conjunctivae of both IMM/S and IMM/R animals could be sensitized passively by intraperitoneal injection of guinea pig sera containing homocytotropic antibodies to OA, but topical administration of such sera had no effect. [ABSTRACT FROM AUTHOR]

ALG raised against lymphoblasts grown in pure culture for many generations contained antiplatelet activity. The thromboaggkitinins could be completely removed by absorption with lymphoblasts, indicating that they had been raised to antigens shared by lymphoblasts and platelets. Anti-spleen ALG possessed levels of such anti-platelet antibodies but in substantially higher titres, because an additional contribution was made by contaminating thrombocytes in the immunizing injectate. By chromatographic separation and immunoelectrophoretic analysis of the eluate from platelet-antibody complexes generated during the absorption of anti- spleen ALG with thrombocytes, the thromboagglutinins were shown to reside almost exclusively (977%) in the area of the IgA fraction. The direct Coombs' reacting platelets from patients receiving equine anti-spleen ALG with guinea-pig antisera against normal horse serum, showed a highly significant, but not in Variable correlation with clinical platelet depression, which was not, however, clearly related to the thromboagglutinin titre of the ALG being administered. [ABSTRACT FROM AUTHOR]

About 50 per cent of guinea-pigs immunized with egg albumin possess strong antibody activity in an immunoglobulin class with antigenic properties different from those of the well-known guinea-pig immunoglobulins. This immunoglobulin is present in normal guinea-pig serum in very small amounts and its concentration rises during immunization with egg albumin. Immunization with bovine insulin or bovine γ-globulin does not stimulate increased synthesis of this immunoglobulin class. Owing to the special conditions that are needed for its stimulation it is provisionally called IgS. It was found to be a heat stable 6·5S immunoglobulin and is not involved in PCA reactions. [ABSTRACT FROM AUTHOR]

Methods for isolation and purification of precipitating and non-precipitating guinea-pig antibodies are described. The physicochemical properties of γ1 and γ2 non-precipitating antibodies are similar to γ1 and γ2 precipitating ones. Biological properties are also similar excepting the reverse Arthus reaction, which is positive with the precipitating and negative with the non-precipitating antibodies. Bivalence of these antibodies was experimentally demonstrated. Precipitating antibodies Ko do not differ greatly from those obtained with the corresponding non-precipitating ones. The incapacity to precipitates with the antigen may be a consequence of a steric impediment. [ABSTRACT FROM AUTHOR]

It is suggested that guinea-pigs produce three different homocytotropic antibodies that can be distinguished by their physicochemical and biological properties. One has the properties of an IgG antibody, is heat and mercaptoethanol resistant and persists in the passively sensitized skin for not more than 72 hours. The other has the properties of an IgE antibody, is heat and mercaptoethanol labile and persists in the passively sensitized skin for at least 20 days. The third antibody is heat stable and mercaptoethanol labile and persists in the passively sensitized skin for more than 72 hours but less than 1 week. This antibody was partially separated from γ1 antibody by chromatography on DEAE cellulose and may represent a distinct segment of the γ1 antibody population. All three antibodies were able to sensitize guinea-pig mast cells and cause degranulation of these cells on reaction with antigen. Antihistamines produced complete inhibition of PCA reactions induced with all three types of antibodies but were much less efficient in inhibiting PCA reactions induced with γ1 antibody obtained from hyperimmune serum. [ABSTRACT FROM AUTHOR]

Four experimental procedures leading to lower antibody production, namely administration of a minute amount of antigen or excess of antigen, competition with an unrelated antigen and treatment with methotrexate, were studied for their effect on each of the forms of immunological responses in guineapigs to a DNP-BSA conjugate. It was found that delayed hypersensitivity and 2-ME sensitive antibody production were more reduced by administration of excess of antigen or by competition than by giving a minute amount of antigen or methotrexate. On the other hand, IgG1 production was more suppressed in the groups receiving minute amounts of antigen or methotrexate treatment than in those given excess of antigen or subjected to competition. IgG2 production was markedly reduced in all four groups of animals. However, excess of antigen and competition changed the kinetics of both total antibody and IgG antibody production (peak on day 20 after immunization). The peak of total as well as IgG2 antibody-production in the groups given a minute amount of antigen or methotrexate, was on day 35, the same as in optimally immunized animals. These results suggest that a common mechanism for reduction of the immune response may be responsible for the excess of antigen and competition effects on one hand and the minute amount of antigen and methotrexate effects on the other. Competition with an unrelated antigen and excess of the same antigen could both act on the same effector cell. Methotrexate could act not only by killing a proportion of immunologically competent cells, but also by lowering their sensitivity to stimulation by antigen. [ABSTRACT FROM AUTHOR]

The reported observations on the slow, low-grade lysis of EAC1-8 were re-examined by using antisera to guinea-pig C9 as a specific inhibitor against C9 to eliminate the possibility that C8 preparations might contain C9 which lyses EAC1-8. Pretreatment of C8 preparation with IgG fraction of the anti-C9 did not result in reduction of the degree of lysis of EAC1-7 by C8. The dose respone curve in titration of C8 with EAC1-7 in the absence of C9 was sigmoidal and completely different from that in the presence of excess C9, suggesting that the cell membrane damage caused by C8 might not be the same as that by C9. Sensitized nucleated cells were shown to be lysed similarly by the first eight components of complement, namely C1 to C8 [ABSTRACT FROM AUTHOR]

The localization of rabbit γ-globulin was traced in the thyroids of guinea-pigs receiving rabbit anti-guinea-pig thyroglobulin serum intravenously. The fluorescent antibody technique was used. Rabbit γ-globulin was found in the interstitium and pericapsular region ¼ hour after the injection, and could be seen there for 24 hours. Five, 10 and 20 days after injection the interstitium was free of specific green-fluorescence. The first sign of specific fluorescence, associated with the epithelial cells, was seen as rounded droplets of fluorescent material after 1 hour. Thereafter, these droplets could be found, increasing in size, at all time intervals later studied. Twenty-four hours after injection green-fluorescent material was seen in some of the follicular lumina. However, most of these did not display any specific fluorescence. Granulocytes showing specific fluorescence were first observed 1 hour after injection, but this phenomenon was most evident at 12 and 24 hours. Both eosinophil and neutrophil granulocytes were found in the infiltrates, but it could not be decided whether both of these cell types were involved in the uptake of rabbit γ-globulin. The findings were discussed in relation to the previous reported observation of strongly PAS-positive material in the granulocytes. Together the observations suggested the uptake of both antigen and antibody, most probably as an antigen-antibody complex. The relevance of the observations in relation to thyroid physiology, as well as to experimental thyroiditis after active immunization and to chronic nonspecific human thyroiditis is discussed. [ABSTRACT FROM AUTHOR]

Guinea-pigs injected with testis autoclavate (WT) in incomplete adjuvant develop antibody but no delayed hypersensitivity or testicular lesions. These animals fail to develop delayed hypersensitivity or a lesion when subsequently injected with antigen in complete adjuvant. Animals similarly treated, and then given repeated injection of immune cells from animals treated with whole testis and complete adjuvant, develop both delayed hypersensitivity and the characteristic orchitis. Guinea-pigs injected with a purified fraction (designated H) with incomplete adjuvant fail to develop either circulating antibody, delayed hypersensitivity or a testicular lesion. Animals subsequently injected with this antigen and complete adjuvant, develop delayed hypersensitivity but no circulating antibody or testicular lesion. Three of the five animals similarly treated and given repeated injections of serum containing anti-testis antibody also develop orchitis. A sequential study of fourteen animals killed at daily intervals after they were injected with WT and complete adjuvant, showed that antibody was first detected in the testis on the same day as delayed hypersensitivity first appeared. Circulating antibody was not detected until 2 days later. The specific testicular antigen showed first signs of disappearing on the 10th day, by which time histological evidence oforchitis was first detected. Antibody was not detected in the testes in any animal in the absence of delayed hypersensitivity. [ABSTRACT FROM AUTHOR]

Young immature guinea-pigs, 7–10 weeks old, were exposed to X-rays directed solely to the thymus gland which received a tissue dose of 300 r. An equal number of animals were not irradiated. All the animals had an intracardiac injection of 0·3 ml of Indian ink containing 10 per cent carbon of uniform particle diameter. An increase in number and size of Hassall's corpuscles was noted in irradiated thymus glands. Simultaneously, there was an increase in the uptake of carbon in the walls of blood vessels and in perivascular macrophages. Within 12 hours of irradiation Hassall's corpuscles contained carbon, at first in a finely stip- pled form in polymorphonuclear leucocytes and, later, in larger aggregates in macrophages. After an interval of 14 days Hassall's corpuscles disappeared and the lobules were re-populated with thymocytes. Migration outwards of carbon laden macrophages occurred between the 14th and 21st days. By contrast the entry of carbon in control glands took place more slowly but retention of particulate matter in Hassall's corpuscles was still present at the end of the experimental period of 56 days. It is suggested that Hassall's corpuscles are a ‘graveyard’ for dead thymocytes, possibly for some effete circulating lymphocytes and in some circumstances for polymorphonuclear leucocytes. It is also suggested that antigens localize in Hassall's corpuscles. Furthermore, since γ-globulin is known to localize there, these antibodies may be mobilized and returned to the circulation by macrophage activity. [ABSTRACT FROM AUTHOR]

γG-globulins† from human syphilitic sera when treated with pepsin are still capable of flocculating cardiolipin antigen but lose their ability to fix guinea-pig complement in the presence of antigen. [ABSTRACT FROM AUTHOR]

Guinea-pigs were immunized by injections of blood group substance with incomplete adjuvant, followed after an interval of approximately 2 weeks, by intracutaneous immunization with the same antigen and Freund's adjuvant containing M. tuberculosis. This treatment inhibited the appearance of delayed skin reactions, while circulating antibody production took place as in controls which had received complete adjuvant only with blood group substance, and had delayed skin reactions. The inhibition of the skin reaction was found to be antigen-specific with regard to unrelated antigens, but showed cross-inhibition for serologically different human blood group substances. The first immunization had to be given more than 2 days before the immunization with complete adjuvant. A similar phenomenon was seen with ovalbumin as antigen. In addition to inhibition of the delayed skin reaction, there appeared to be less γ2-antibody to ovalbumin than in ovalbumin plus complete adjuvant-only controls. Passive administration of antibody did not affect the development of a delayed hypersensitivity state in complete adjuvant-immunized animals with blood group substance or ovalbumin as antigen. Present evidence favours an explanation of the phenomenon in terms of temporary paralysis on the part of some of the antibody-producing cells—viz. those concerned with delayed hypersensitivity and γ2-antibody production. [ABSTRACT FROM AUTHOR]