FC-GAMMA-RECEPTOR-III (CD16) IS INVOLVED IN NK-B CELL-INTERACTION

CD16, the low affinity receptor for monomeric IgG (Fc gamma RIIIA), is a well characterized activation molecule on NK cells. In this study w e investigated the role of CD16 in NK cell-mediated regulation of immu noglobulin production. Cocultures of the CD16(+) human NK clone CNK6 a nd highly purified SAC/IL-2-activated B lymphocytes with various CD16 antibodies showed significantly diminished NK-enhanced immunoglobulin production in a dose-dependent manner, indicating that CD16 is relevan t in NK-B cell interaction. Similarly, recombinant soluble CD16 incuba ted with B cells before cultures, suppressed the NK cell-stimulated B cell antibody response. Enhanced immunoglobulin production was also in hibited by Fc-specific F(ab')(2) antibody fragments. Coculture of NK c ells with B lymphocytes resulted in induction of mRNA for IFN-gamma an d TNF-alpha. The accumulation of mRNA for these cytokines was prevente d by addition of CD16 and Fc-specific antibodies. It is proposed that interaction of CD16 on NK cells with B cell bound immunoglobulin leads to induction of cytokines in NK cells which stimulate immunoglobulin production by B cells.