Immunological properties of Fc receptor on lymphocytes. 9. Functional analysis of FcR gamma+ and FcR gamma- lymphocytes in IgE antibody responses.

The present study was undertaken to clarify the function of FcR gamma+ and FcR gamma- lymphocytes in anti-DNP IgE antibody responses. The helper activity was observed predominantly in FcR gamma- T cells, but poorly in FcR gamma+ T cells, as in the case of IgG antibody responses, indicating that the absence of FcR gamma on T cell surface is a common surface characteristic to helper T cells, and that there is no close relationship between the determination of class specificity of Ig and T cell subsets divided by the presence or absence of FcR gamma. Furthermore, IgE antibody responses were more dependent upon helper T cells than IgG antibody responses. The data presented in this paper also demonstrated that the precursors of anti-DNP IgE antibody-forming cells were equally contained in both FcR gamma+ and FcR gamma- B cells, when they were transferred into recipients with helper T cells. This is a striking contrast to IgM/IgG antibody responses, in which only FcR gamma- B cells could differentiate into antibody-forming cells. Moreover, the precursor activity of FcR gamma+ and FcR gamma- B cells for IgE antibody-forming cells was not affected by the treatment of cells with suppressive B cell factor released from FcR gamma+ B cells after binding of antigen-antibody (IgG) complexes and known to suppress the proliferation of FcR gamma- IgM/IgG antibody-forming cell precursors. Thus, IgE B cells seem to be more heterogeneous than IgM/IgG B cells with respect to the FcR gamma marker and insensitive to the regulatory effect of FcR gamma+ B cells. IgE B cells are regulated differently from IgG B cells in B-B cell interactions.