Functional analysis of suppression in MLRs. Multiple neutralizing antibodies and fusion proteins were screened for functional effects on suppression in CD4+ T-cell DC-MLR. (A) Antibodies to immunosuppressive factors IL-10 and TGF-β as well as anti–IL-10R or combinations of all 3 fail to reverse suppression mediated by cultured Treg cell lines. (B) Antibodies to negative signaling molecules, CTLA4 and PD1, do not reverse suppression. (C) Antibodies to GITR or GITR-L do not effect suppression. Agonist antibodies to OX40 partially reverse suppression while antibody to OX40L partially enhances suppression. (D) Multiple TGF-β–neutralizing antibodies and soluble receptors do not prevent suppressor cell effector function. Treated MLRs are indicated by gray bars and treated MLRs plus Ts cultures by burgundy bars. Representative of 6 independent experiments for panels A-C and 3 independent experiments for panel D.
