In vivo cyclic change in B-lymphocyte susceptibility to T-cell control

The humoral response to hapten-protein conjugates is an invaluable model for dissecting the cellular elements of lymphocyte cooperation, and the Mitchison secondary adoptive transfer system provides convincing evidence of cooperation between hapten-specific B cells and carrier-specific T cells in the production of anti-hapten antibody. Recently, attention has focused on the role of suppressor T cells in the regulation of antibody production. Several workers have shown that carrier-priming may, in some instances, suppress a subsequent hapten antibody response, both in vivo and in vitro. This effect is attributed to a suppressor T-cell population, generated during the initial phase of the immune response. Gershon and co-workers have postulated that such suppressor T cells function in a feedback regulatory loop to limit the duration of an immune response. We have examined the suppressive effect of carrier immunization in a secondary anti-hapten response in vivo and demonstrate a cyclic change in susceptibility of memory B cells to T-help and suppression. Such variation presents a severe restriction to any model of feedback control by suppressor T cells.