Regulation of in vivo Expression of Fc Receptors for IgE (FcεR) on Murine Lymphocytes

Abstract

Homologous monomeric IgE was employed in a flow cytometric assay for the detection of IgE Fc receptors (Fc epsilon R) on mouse lymphocytes. The expression of Fc epsilon R in normal BALB/c mice was detected on splenic and circulating lymphocytes, but not on bone marrow cells. The Fc epsilon R expression was observed in B cells with B220, surface IgM, and IgD, but not in T cells. Infection of mice with Nippostrongylus brasiliensis resulted in a marked increase in the expression of Fc epsilon R on splenic B cells. T cells, however, did not express Fc epsilon R even after N. brasiliensis infection. On the other hand, the Fc epsilon R expression on normal B cells decreased after a simple incubation at 37 degrees C for 24 h, while in the presence of IgE this decrease was inhibited. In contrast, B cells stimulated with interleukin 4 display Fc epsilon R with high densities. Interestingly, IgE enhanced the Fc epsilon R expression induced by interleukin 4, suggesting that both interleukin 4 and IgE may be responsible for an increase in the expression of Fc epsilon R on B cells of N. brasiliensis infected mice.