Large scale preparation of human MHC class II+ integrin beta(1)+ Tregs.

The human CD4+CD25+FoxP3+ regulatory T cell population (Tregs) contains both MHC class II+ and MHC class II(-) cells. MHC class II+ Tregs belong to the integrin alpha(4)beta(1)+ subpopulation and exclusively execute contact-dependent suppressive activity. Here we present a method optimized for isolation of these MHC class II expressing Tregs from large leukaphereses products using magnetic microbeads that achieves a reproducible purity of more than 90% and enables the use of this small-sized Treg population in pre-clinical application and basic research.

Monoclonal antibodies specific for the IL-18 receptor.

Interleukin-18, a pleiotropic cytokine is a member of the IL-1 family and has multiple immunoregulatory functions. IL-18 action leads to IFNgamma production by NK or T cells, induces Th1 differentiation and suppresses IgE synthesis by B cells when acting on responding cells in association with IL-12. At present two subunits of the IL-18R have been characterized: IL-18 Ralpha and IL-18 Rbeta. Both receptors belong to the IL-1R family. IL-18 Ralpha has been described as the ligand-binding chain and IL-18 Rbeta as the signal-transduction chain. Three monoclonal antibodies (mAbs) submitted to the HLDA8 workshop, designated H44 (80438), B-B46 (80228), and B-E43 (80232) were evaluated. The mAb specificity was determined by ELISA using coated recombinant IL-18 Ralpha or IL-18 Rbeta. Cell staining was analyzed by flow cytometry. A positive staining with the mAb B-E43 or H44 demonstrated that IL-18 Ralpha is expressed on several myeloid cell lines. No positive cell staining was observed with the anti IL-18 Rbeta mAb B-B46. The mAb biological activity was studied using the cell line KG1. A downmodulation of IFNgamma production was observed with the mAbs B-B46 (80228) and B-E43 (80232).

Characterization of monoclonal antibodies directed against trail or trail receptors.

A subset of tumour necrosis factor receptor family members is involved in death transducing signals and is, therefore, referred as the "death receptors." Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in many tumour cells but only rarely in normal cells. Five distinct receptors have been described for TRAIL: TRAIL R1 (DR4), TRAIL R2 (DR5, TRICK), TRAIL R3 (TRID, DcR1), TRAIL R4 (TRUNDD, DcR2), and osteoprotegerin. In the Eighth International Workshop on Human Leukocyte Differentiation Antigens, 10 monoclonal antibodies (mAbs) reported to be specific for TRAIL or for TRAIL receptors were submitted. In the present study, the mAb specificity was determined by ELISA. Using these mAbs, investigation on the expression of TRAIL and TRAIL receptors was performed. Some of them were able to modulate TRAIL induced programmed cell death.