Reactivity of monoclonal antibody B-ly7 with a subset of activated T cells and T-cell lymphomas.

Antibody B-ly7 is reactive with hairy cell leukemia and a small subpopulation of normal lymphocytes. The B-ly7 antigen can also be induced on normal peripheral blood lymphocytes by phorbol ester stimulation. Recently it has been found that the reactivity pattern of B-ly7 is similar to that of HML-1, an antibody reactive with mucosal T lymphocytes and so called enteropathy associated T-cell lymphomas. Reactivity of B-ly7 with 6/61 peripheral T-cell lymphomas, including two intestinal and four extraintestinal cases, is described. The intestinal cases were CD8 and CD7 positive, whereas the extraintestinal cases were CD4 positive and CD7 negative. Activation of purified peripheral blood T cells resulted in approximately 20% B-ly7+ T cells at Day 3. Approximately 75% of the B-ly7+ cells were CD8+, whereas the remainder were CD4+. The results indicate that B-ly7 as well as HML-1 recognize an activation-associated antigen that is expressed on small normal T-cell and B-cell populations and can be induced on a relatively high proportion of T and B cells in vitro.