Spleen and lymph node cells from AKR mice with spontaneous leukemia are able to suppress the in vitro antibody responses of normal cells. This suppression requires cell contact and has genetic restriction. The suppression can be carried out by isolated membranes of leukemic cells. DNase treatment of leukemic cells abrogates the suppression by both cells and membranes. This research will determine if suppression of cell mediated responses are also overcome by DNase and if membranes are able to suppress these reactions.