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Objective: IL-35 is the most recently identified member of the IL-12 family. It consists of EBV-induced gene 3 (EBI3) and IL-12α chain p35. We investigated whether IL-35 enhances the in vitro immunosuppressive function of peripheral blood isolated from patients with RA., Methods: Peripheral blood was harvested from 17 active and 10 inactive RA patients and IL-35 concentrations were quantified using an ELISA. An expression vector containing IL-35 with a FLAG tag at the carboxyl-terminus was constructed by covalently linking EBI3 and IL-12α (p35). The function of IL-35 was then evaluated in a suppression assay using T cells isolated from human RA patients with CD2, CD3 and CD28 antibodies., Results: Serum IL-35 levels and the number of Treg were decreased significantly in patients with active RA. There was a significant correlation between serum IL-35 and the 28-joint DAS with ESR (DAS28-ESR) in patients with active RA. IL-35 treatment enhanced the regulatory function, suppressing the levels of inflammatory cytokines such as IL-17 and IFN-γ and the cellular growth of effector T cells stimulated by conjugation with CD2, CD3 and CD28., Conclusion: These data revealed that IL-35 might suppress T cell activation during the peripheral immune responses of RA. Therefore our data suggest that IL-35 might have multiple therapeutic targets., (© The Author 2015. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Objectives: We sought to determine the significance of bright CD45 expression on mast cells in cases of systemic mastocytosis vs mast cells in bone marrows uninvolved by systemic mastocytosis and compare this CD45 expression with CD25 and CD2 expression on mast cells., Methods: Multiparameter flow cytometry was performed on 31 cases of systemic mastocytosis and 70 bone marrow cases that were not involved by systemic mastocytosis. Bright expression of CD45 was defined as more than 20% of CD117+ mast cells showing brighter CD45 expression than the average expression level of lymphocytes., Results: Mast cells with bright CD45 expression were seen in 26 systemic mastocytosis cases and three bone marrows uninvolved by systemic mastocytosis (sensitivity, 84%; specificity, 96%). CD25 alone had a greater sensitivity (100%) but lower specificity (93%) compared with bright CD45 for identifying abnormal mast cells, while CD2 alone had lower sensitivity but higher specificity. To reach a specificity of 100%, CD25 together with bright CD45 on mast cells was the optimal combination to detect cases of systemic mastocytosis., Conclusions: A combination of bright CD45 and CD25 appears to specifically identify abnormal mast cells in cases of systemic mastocytosis. Further studies will be necessary to confirm these results., (Copyright© by the American Society for Clinical Pathology.)

Human lamina propria T lymphocytes (LPT) possess functional properties profoundly different from those of peripheral blood T lymphocytes (PBT). While they are characterized by a low proliferative response to T cell receptor (TCR)/CD3 stimulation in vitro their responsiveness to activation through the 'co-stimulatory' CD2-receptor is enhanced when compared to PBT. In this study, we demonstrate that engagement of another co-stimulatory receptor on both LPT and PBT, namely CD28, by a single monoclonal antibody (mAb), respectively, strongly activates the former but not the latter through a PI3-kinase dependent signalling pathway leading to the production of inflammatory cytokines such as interleukin (IL)-2, tumour necrosis factor (TNF)-α, interferon (IFN)-γ and granulocyte-macrophage colony-stimulating factor (GM-CSF). In addition to the high sensitivity of LPT to CD2 stimulation, this finding supports the notion that 'non-specific/innate' mechanisms to activate T lymphocytes play a predominant role vis-à-vis'TCR driven/adaptive' responses in the intestinal mucosa. Furthermore, it suggests that results from preclinical tests for therapeutic antibodies performed with human blood derived T cells are probably insufficient to predict reactivities of tissue-resident immune cells, which--given their quantitative predominance--may critically determine the in-vivo response to such compounds., (© 2011 The Authors. Clinical and Experimental Immunology © 2011 British Society for Immunology.)

Background: CD2-associated protein (CD2AP) is a crucial protein for the slit-diaphragm assembly and function. In spite of the fact that CD2AP knockout causes nephrotic syndrome in mice and the heterozygous +/- mouse is prone to proteinuria, little is known about the relevance of this molecule in human renal pathology., Methods: A total of 80 Italian patients with idiopathic nephrotic syndrome were enrolled and screened for changes in the CD2AP gene. A normal control group of 200 healthy donors was also studied. The coding region of the CD2AP gene was analysed by polymerase chain reaction, denaturing high-performance liquid chromatography and sequencing. Peripheral blood mononuclear cells from patients with CD2AP mutations and from healthy donors were isolated by the Ficoll-Hypaque gradient, and the CD2/CD2AP interaction was studied on T-lymphocytes by confocal laser scanning microscopy analysis. The expression levels of CD2AP, nephrin and podocin proteins were evaluated by indirect immunofluorescence on renal biopsies from a patient with p.delGlu525 mutation and from control subjects. Moreover, the effect of the p.K301M mutation on cell viability was evaluated by flow cytometry and annexin V/propidium iodide staining., Results: Three heterozygous mutations (c.904A>T; c.1120A>G; c.1573delAGA) producing respectively aminoacidic changes (p.K301M, p.T374A) or a deletion in functional domains (p.delGlu525) were found in three unrelated patients. One (p.K301M) produced a lysine to methionine change in the third interactive SH3 domain (position 301) and resulted in the defective CD2-CD2AP interaction and clustering; the other (c.1573delAGA) caused the deletion of the glutamic acid in position 525 in the COOH-terminal region of binding with nephrin and was associated with down-modulation of CD2AP, podocin and nephrin glomerular expression., Conclusions: Our findings suggest that CD2AP mutations modify the interaction with CD2 in lymphocytes and alter the composition of the renal slit diaphragm.

Sequences proximal to transgene integration sites are able to deregulate transgene expression resulting in complex position effect phenotypes. In addition, transgenes integrated as repeated arrays are susceptible to repeat-induced gene silencing. Using a Cre recombinase-based system we have addressed the influence of transgene copy number (CN) on expression of hCD2 transgenes. CN reduction resulted in a decrease, increase or no effect on variegation depending upon the site of integration. This finding argues that repeat-induced gene silencing is not the principle cause of hCD2 transgene variegation. These results also suggest that having more transgene copies can be beneficial at some integration sites. The transgenic lines examined in this report also exhibited a form of imprinting, which was manifested by decreased levels of expression and increased levels of variegation, upon maternal transmission; and this correlated with DNA hypermethylation and a reduction in epigenetic chromatin modifications normally associated with active genes.

Acute myeloid leukemia (AML) with pseudo-Chèdiak-Higashi (PCH) anomaly is a rare morphologic entity. We characterized 5 cases by multiparameter flow cytometry and found that in all cases, the blasts aberrantly expressed CD2, a pan-T cell-associated marker, in addition to their myeloid-associated markers. In contrast, CD2 was expressed in only 25 (17.9%) of 140 cases of newly diagnosed AML without PCH anomaly. CD2 expression correlated strongly with AML with PCH anomaly (P < .01), suggesting a link between a specific immunophenotypic marker, CD2, and AML with PCH anomaly.

High-throughput gene trapping is a random approach for inducing insertional mutations across the mouse genome. This approach uses gene trap vectors that simultaneously inactivate and report the expression of the trapped gene at the insertion site, and provide a DNA tag for the rapid identification of the disrupted gene. Gene trapping has been used by both public and private institutions to produce libraries of embryonic stem (ES) cells harboring mutations in single genes. Presently, approximately 66% of the protein coding genes in the mouse genome have been disrupted by gene trap insertions. Among these, however, genes encoding signal peptides or transmembrane domains (secretory genes) are underrepresented because they are not susceptible to conventional trapping methods. Here, we describe a high-throughput gene trapping strategy that effectively targets secretory genes. We used this strategy to assemble a library of ES cells harboring mutations in 716 unique secretory genes, of which 61% were not trapped by conventional trapping, indicating that the two strategies are complementary. The trapped ES cell lines, which can be ordered from the International Gene Trap Consortium (http://www.genetrap.org), are freely available to the scientific community.

Objective: In our laboratory, we have developed an immunorosette technique for the depletion of T cells from bone marrow transplants. Tetrameric complexes of monoclonal antibodies are able to form very stable immunorosettes, which are efficiently depleted with the aid of a blood cell separator. Major improvements over the original sheep red blood cell depletion are the use of human (patient or donor derived) erythrocytes instead of sheep-derived cells, and the possibility of using a closed system for separation in a cell separator. In contrast to bone marrow, mobilized haematopoietic stem cell transplants obtained after leucocytapheresis contain higher numbers of T cells. Therefore, a different approach is necessary., Method: We have used two CD34 selection systems (Isolex 300SA and the Clinimacs) to perform T-cell depletions from peripheral blood stem cell (PBSC) transplants., Results: Immunorosette T-cell depletion, with CD2/CD3 tetrameric complexes, of bone marrow transplants resulted in a mean 2.5 log depletion of T cells with a yield of 50% of the CD34+ cell population. Stem cell selection of PBSC transplants using one of the CD34 selection procedures resulted in a 4.5 log depiction of T cells for both systems, but with different results for the recovery of CD34+ cells. An increased yield of CD34+ cells was obtained with the Clinimacs procedure (57.9+/-9.0%) in comparison to the Isolex procedure (40.1+/-12.5%)., Conclusion: Our own immunorosette depletion technique and the two tested CD34 selection methods for stem cell transplants both resulted in a very efficient T-cell depletion with the recovery of 40-60% of the CD34 haematopoietic stem cells present in the transplant.

Human intraepithelial lymphocytes (IEL), CD8+ lymphocytes located between epithelial cells, are likely to be influenced by the immunosuppressive cytokine, TGF-beta, secreted by epithelial cells. This study evaluates the effects of TGF-beta on IEL functions. IEL were derived from proximal jejunum of patients undergoing gastric bypass operations for morbid obesity. Proliferation was determined by 3H-thymidine incorporation; IL-2 production, by ELISA; expression of IL-2 receptor, CD2, HML1, CD16, and CD56, by immunofluorescence; binding, by adherence of radiolabelled cells; and cytotoxicity by 51Cr-release assay. TGF-beta (> or = 1 ng/ml) inhibited the mitosis of IEL to mitogens, IL-7, and stimuli of the CD2 and CD3 pathways. The blocking effect did not target the activation events of IL-2 production and receptor generation. Rather, it reduced cell division after activation when added 24 h after initiating the culture. Antibody neutralization of naturally occurring TGF-beta increased IEL proliferation to IL-2, but not to the other stimuli. Of the multiple surface markers tested, only CD2 and HML1 expression increased with TGF-beta and decreased with antibody to TGF-beta, although the cytokine and the neutralizing antibody had no effects on IEL binding to colon cancer. TGF-beta reduced the number of CD56+ IEL and the lymphokine-activated killing when co-cultured with IL-7 but not with IL-2 or IL-15. TGF-beta inhibits certain IEL functions: the reduction in cell division rather than activation and a decline in IL-7-mediated lysis of colon cancer due to a lowering of the number of natural killer cells.

Apoptosis is a highly conserved form of cell death present in all eukaryotic cell types and controlled by multiple genes. Several methods have been developed to quantify apoptosis, but none is adapted for all cell types. It is particularly difficult to reliably assay apoptosis of adherent cells. We describe a new, rapid and reliable flow cytometric method which can be used for quantifiying apoptosis in a sub-population of transiently transfected adherent cells. This technique is based on the detection of transfected cells and the apoptotic sub-population by immunofluorescence and Annexin-V labelling, respectively.

Signaling through the leukocyte function-associated antigen 1 (LFA-1) molecule has previously been shown to induce homotypic aggregation in T cells and to induce cytoskeletal changes in T lymphoma cells. In this study we describe the induction of a dendritic phenotype associated with cytoskeletal rearrangement in activated human peripheral blood T cells stimulated with monoclonal antibody SPV-L7 to LFA-1 alpha. Maximal expression of this phenotype required 72 h preactivation with phorbol myristate acetate and expression was abolished using the protein kinase C inhibitor staurosporine. Monoclonal antibody to CD18, the beta-chain of LFA-1, did not induce this phenotype. Monoclonal antibody MEM 83 to presumably a discrete epitope on LFA-1 alpha did not induce this phenotype but induced homotypic aggregation. However, a monoclonal antibody to CD44 induced a similar phenotype in activated lymphocytes. Induction of both homotypic in activated lymphocytes. Induction of both homotypic aggregation and the dendritic phenotype was abolished by preincubation with soluble intracellular adhesion molecule 1 (ICAM-1). Cytoskeletal inhibitors prevented the morphological changes in SPV-L7-activated lymphocytes. Preincubation with tyrosine kinase inhibitor, protein kinase C inhibitors, and inhibitors of new protein synthesis also prevented these morphological changes. These data suggest that discrete epitopes on LFA-1 alpha may be capable of inducing discrete signals either for homotypic aggregation or for a dendritic phenotype. As both LFA-1 and CD44 are involved in the migration of lymphocytes through high endothelial venules, these data could suggest that these molecules transduce signals resulting in cytoskeletal modification necessary for lymphocyte transmigration.