Modulatory anti-T antibody on mature human lymphocytes.

A monoclonal antibody developed in our laboratory, designated AN1, was investigated using in vitro cellular techniques. We found that this antibody modulates cell activation depending on the stimulatory signal used. Autologous and allogeneic MLR or MNC activated by mitogens like PHA and antigen like PPD, are all inhibited by the antibody. The inhibition takes place at an early stage of the cell activation pathway and cannot be reversed by exogenously added IL-2. The MNC activated with phorbol esters like TPA, on the other hand, showed enhancement in response to this antibody, whereas OKT3-activated cells are unaffected. This antibody is also found to inhibit specific CTL but has no affects on NK activity. The tissue distribution of the antigen(s) detected by our antibody showed that it is specific for mature unactivated human T cells and furthermore the target antigen(s) disappeared as a result of cell activation. The implications of these findings are discussed.