抄録
In our previous paper, we reported that guinea pig splenic lymphocytes expressed two distinct Fc-receptors for homologous IgG (FcγRs), one monospecific for IgG2 (Fcγ2R) and the other bispecific for IgG1 and IgG2 (Fcγ1/γ2R), when analyzed by EA-rosette assay. These FcγRs on the cells were further studied by using two monoclonal antibodies toward the FcγRs on guinea pig peritoneal macrophages (anti-Fcγ1/γ2R and anti-Fcγ2R antibody). The anti-Fcγ1/γ2R antibody completely inhibited the rosette formation of splenic lymphocytes with IgG1-sensitized sheep erythrocytes [EA(IgG1)]. On the other hand, EA(IgG2)-rosette formation was inhibited partially by anti-Fcγ2R but not by anti-Fcγ1/γ2R antibody. Complete inhibition of the EA (IgG2)-rosette formation was achieved by simultaneous additions of both anti-Fcγ2R and anti-Fcγ1/γ2R antibodies. The binding of IgG2 antibody complexed with ovalbumin to the cells was partially inhibited by either anti-FcγR antibody, and complete inhibition occurred in the presence of both the antibodies, indicating that two types of FcγR, Fcγ1/γ2R, and Fcγ2R, are expressed on the cells. The determination of these FcγRs on B and T lymphocytes by two-color flow cytometry showed that about 52% of B lymphocytes expressed Fcγ1/γ2R alone and 32% of the cells expressed both the FcγRs. On the other hand, about 12% of T lymphocytes was found to express Fcγ2R alone and the cells expressing Fcγ1/γ2R were in the minority (3.8%). T lymphocytes expressing both the FcγRs were not detected. These results show that guinea pig B lymphocytes bear two types of FcγRs and are heterogeneous with regard to their FcγRs and that T lymphocytes express Fcγ2R mainly.
