Alloantigens expressed on a subset of unstimulated human T lymphocytes that generate suppressor function.

Human alloantisera were tested for antibodies reacting with T-cell subpopulations. T-cell subsets were separated using the monoclonal antibodies OKT4 and OKT8. Five sera reacting with the T4-T8+ subset and two sera reacting with T4+T8- lymphocytes were identified. Serum Z. G. reacted with T4-T8+ cells from 8 of a panel of 19 donors. T cells treated with Z. G. serum and rabbit complement lost the capacity to generate suppressor cells but showed no decrease in the development of cytotoxic effector cells. ZG antigens were demonstrated by absorption also on monocytes but not on B cells. Their reactions on T cells were blocked by chicken anti-human Ia serum, but not by turkey anti-beta 2-microglobulin or by a monoclonal anti-human DR (L227). Studies in four informative families suggested that the ZG determinants are inherited in linkage with HLA. Although the similarities between ZG antigens and mouse I-J products are striking, structural studies are needed to establish their homology.