Immunological properties of Fc receptor on lymphocytes. VIII. The behaviour of FcR+ and FcR- T cells in cell-mediated immune responses.

The roles of splenic FcR+ and FcR- T cells from mice immunized either with allogeneic cells or with LCMV or stimulated either with MMC-treated allogeneic cells or TNP-modified syngeneic cells in vitro were examined for cell-mediated cytolytic responses. Effective lysis was observed in the FcR- cell fraction enriched with nylon wool eluted T cells in all experiments. Killer cells were generated from the FcR- T-cell fraction after exposure to either allo-, virus- or chemically modified antigen. On the other hand, the lytic activity of the FcR+ T-cell fraction, was low but nevertheless still significant. However, this weak cytotoxicity was increased by 24 h of incubation, although the recovery of living cells was found to be significantly lower in the FcR+ than in the FcR- T-cell fraction. This suggested that non-killer cells, which could interfere with the activity of pre-killer cells, were perhaps preferentially eliminated after binding with the immune complexes. Moreover, almost complete inhibition of lytic activity was achieved in allo-activated FcR+ T, but not FcR- T-cell fraction, after they had been treated with immune complexes, implying a functional significance of FcR in the manifestation of lytic activity.