Regulation of in vivo expression of Fc receptors for IgE (Fc epsilon R) on murine lymphocytes. II. Induction of Fc epsilon R and its inhibition in mice immunized with antigen

The induction of Fc receptors for IgE (Fc epsilon R) and its regulation were studied in BALB/c, SJL/J, and nude mice by a flow cytometric assay with the use of homologous monomeric IgE. Immunization of BALB/c mice with alum-absorbed antigen induced a remarkable increase in the expression of Fc epsilon R on spleen cells, whereas no enhancement of the Fc epsilon R expression was observed in SJL/J and nude mice after immunization. This increase was correlated with the elevation of serum IgE levels. However, the IgG antibody response, which is inducible even in SJL/J mice, was not associated with the induction of Fc epsilon R. The enhanced expression of Fc epsilon R in BALB/c mice observed in the primary or secondary IgE antibody response was detected in B cells with B220, surface IgM, and IgD, but not in T cells. The induction of Fc epsilon R in immunized BALB/c mice was inhibited by suppressive factor of allergy isolated from ascites fluids of SJL/J mice inoculated with complete Freund's adjuvant. In addition, both cyclophosphamide and prednisolone had an inhibitory effect on the induction of Fc epsilon R. These results suggest that the Fc epsilon R induction is inhibited not only by suppressive factor of allergy, which is effective in inhibiting the IgE antibody response selectively, but also by some immunosuppressive agents which are capable of suppressing all isotypes.