Mechanism of anti-helper cell monoclonal antibody immunosuppression

We investigated in vivo immunosuppression due to two antihelper cell antibodies by determining whether cell clearance was necessary for suppression of the allogeneic delayed-type hypersensitivity (DTH) response. B10.A mice treated with anti-Lyt 1 before sensitization with AKR lymphocytes demonstrated only a partial reduction (65%) in DTH responsiveness despite a 95% loss of the antigen (Table 1). When C57B1/6 mice were tested for DTH to DBA lymphocytes, treatment with anti-L3T4 produced a diminution in the DTH response that was dose dependent. This correlated with a progressive reduction in the L3T4+ cells in the spleen, ablation of the response occurring only with essentially maximal clearance of the L3T4+ cells.