Modification of surface topography of lymphocytes by L-asparaginase.

i.-Asparaginase is a chemotherapeutic agent that is also immunosuppressive, inhibiting both the cellular and hu moral responses. This study deals with the effects of the enzyme on lymphocyte surface receptors to the mitogen concanavalin A. We previously reported that short incu bation of lymphocytes with L-asparaginase leads to a de creased binding of the mitogen to their surface. We now re port that the enzyme is unable to cleave off concanavalin A surface receptors but causes a significant clustering effect on the topographic distribution of such membrane con canavalin A sites. The mechanism of immunosuppression by L-asparaginase thus appears to be due to alteration of surfaces of lymphocytes which probably accounts for its immunosuppressive activity.