Monoclonal antibody (WT 1) directed against a T cell surface glycoprotein: characteristics and immunosuppressive activity.

WT 1, an IgG2a subclass monoclonal antibody, recognizes a human T lineage specific antigen (mol. wt 40,000). This antigen is strongly expressed on thymic T blasts, and on peripheral T cells activated by phytohaemagglutinin, whereas cortical thymocytes and peripheral T cells are moderately positive for WT 1. In contrast, B lymphocytes, myeloid and erythroid cells, including the progenitor cells of these lineages, and terminal deoxynucleotidyl transferase positive cells in the bone marrow, are all WT 1 negative. Binding of WT 1 to T cells is blocked by a previously described antibody (3A1) suggesting that both antibodies bind to the same antigen present on human T cells. WT 1, however, is also reactive with T lymphocytes from rhesus monkeys whereas 3A1 is not. Therefore, the biological effects of WT 1 could be studied in a monkey model. In a skin allograft model, WT 1 was immunosuppressive and induced a marked prolongation of graft survival.