We have made two observations relevant to the immunodeficiency of Hodgkin's disease: (a) Cells released from Hodgkin's tumor do not behave in proliferative cultures as if they are comprised predominately of clones of neoplastic lymphocytes; (b) both lymphocytes and granulocytes from the blood of Hodgkin's patients suppress responses in the mixed leukocyte culture reaction (MLR). Work outlined in this proposal has three major objectives: (a) To determine whether T cells, B cells or monocytes inhibit 3H-thymidine incorporation in the MLR with Hodgkin's disease. To determine this, allogeneic mononuclear leukocytes (MNL) from control donors will be stimulated in culture with irradiated patient MNL, monocyte depleted patient lymphocytes, enriched patient T cells and enriched patient B cells. 3H-thymidine incorporation will be compared. (b) Studies will be done to see if the population of patient cells identified to inhibit MLR responses in the first experiment also inhibit other immune-related responses by MNL from control donors. The responses selected for testing include immunoglobulin synthesis by cultured lymphocytes, lymphocyte mitogenic factor release by T cells cultured with tetanus toxoid, proliferative responses by B cells cultured with this factor produced by B cells from control donors and the MLR. (c) This is the corollary of the preceding experiment. Here responses shown to be inhibited by certain patient cells will be retested with and without cycloheximide pretreated patient cells. The reason for testing with cycloheximide pretreated cells is that cycloheximide is known to functionally inhibit suppressor T cells.