Antigen-specific human T-cell factors: T-cell helper and suppressor factors, immunochemical aspects

Some immunochemical characteristics of a T-cell-derived ovalbumin (OA) antigen-specific helper (ThF120-OA) and a corresponding OA-specific suppressor effector factor (TsF120-AO) are described. These immunoregulatory molecules are retained by columns containing either the insolubilized antigen OA or the lectin ConA, or antibodies specific for the V(H)-region of immunoglobulins, for the β ₂-microglobulin or for Ia-framework determinants. Neither the helper factor nor the suppressor factor showed affinity for antisera specific for immunoglobulin isotypes. In search of a constant-region-like structure in factor molecules, antisera were raised in rabbits using ThF120-OA and TsF120-OA. The results show that antisera raised against ThF120-OA recognize one or more determinants of different antigenic specificities common to human ThF. This common structure is not species-specific since it is also recognized by rabbit antisera to mouse helper factor. It is absent, however, on human TsF120-OA. In the same way, human TsF120-OA was shown to interact with rabbit antisera to human (or murine) suppressor factors of different antigenic specificities, but not with anti-ThF.