FEEDBACK REGULATION OF HUMORAL IMMUNE-RESPONSE .1. EVIDENCE FOR B-SUPPRESSOR CELLS

Abstract

Complete and antigen-specific immune inhibition can be obrained by B [bone marrow-derived] suppressor cells. Transfer of spleen cells from twice-immunized (SRBC [sheep red blood cell]) [mice] to untreated syngeneic recipients resulted in antigen-specific inhibition of the hosts'' immune response. The cell responsible for this phenomenon was the 7S-producing B cell; participation of T [thymus-derived] cells and macrophages was excluded. After a 2nd immunization of the donors, these B cells remained inhibitory for more than 20 wk in the donors and in the recipients after transfer. Passively administered specific Ig[immunoglobulin]G antibody [Ab] caused a similar inhibition of the hosts'' immune response, which lasted for less than 9 wk. The extent of inhibition caused by transfer of hyperimmune cells was parallel to the number of transferred 7S producing celle. Memory cells were present at times when the transferred cell material had lost its inhibitory potency. Inhibition is not caused by the mere presence of these cells. Since the transferred cells regained their inhibitory capacity after non-specific activation with [Serratia marcescens] LPS [lipopolysaccharide], a product of such activated cells, probably the specific 7S Ab, was responsible for the observed inhibition. B cells may serve as suppressor cells in appropriate transfer experiments. This effect is basically mediated by produced IgG and may in its mechanism be identical to the phenomenon of Ab-mediated regulation of humoral immune response.