ANTIBODY-INDUCED DEPRESSION OF THE IMMUNE RESPONSE

Abstract

Studies were made on the mechanism by which humoral antibodies inhibit the immune response against tumor grafts in allogeneic systems and against bacterial antigens, with the specific aim of differentiating between a central antibody effect at the host level and a. peripheral effect at the antigenic level. It was demonstrated that anti- body-coated tumor cells were enhanced in allogeneic hosts compared to uncoated cells inoculated into the same hosts. This indicated that the antibodies acted primarily at the tumor cell level. Attempts were : made to inhibit the capacity of normal lymphoid cells to produce anti-bodies against Salmonella adelaide flagellar antigen by treating the cells in vitro with humoral antibodies directed against the bacteria. Lethally irradiated recipients inoculated with isologous normal lymphoid cells treated with anti-Salmonella serum in vitro, produced anti-Salnibnella antibodies to the same extent as did recipients given untreated lymphoid cells. A prolonged contact between lymphoid cells and antibodies did not result in decreased ability to produce antibodies lymphoid cells taken from recipients given anti-Salmonella serum 11 days previously were fully competent to produce antibodies when transferred to irradiated isologous recipients, which were subsequently injected with Salmonella antigen. However, inhibition of the immune response regularly occurred when the bacteria were coated with specific antibody in vitro prior to their inoculation. Thus, it was not possible to demonstrate an antibody-induced depression of the immunological response of lymphoid cells, whereas successful inhibition was found of the peripheral pathway in the same experimental system.