Lymphocytes Bearing Receptors for IgE

Abstract

Culture of normal rat lymphocytes with rat IgE at 37°C resulted in an increase in the proportion of Fc_εR(+) cells. In agreement with this finding, the ability of normal lymphocytes to bind ¹²⁵I-IgE markedly increased after overnight incubation with IgE. Evidence was obtained that Fc_εR(+) cells were derived from Fc_γR(+) cells. Fc_εR(+) cells were not induced in vitro if Fc_γR(+) cells were depleted from normal lymphocytes before incubation with IgE. Kinetic studies for the induction of Fc_εR(+) cells showed that the majority of Fc_εR(+) cells induced in vitro bore Fc_γR at the early stage of differentiation. The Fc_εR-Fc_γR double-bearing cells converted to Fc_εR signal-bearing cells after further incubation with IgE. It was also found that induction of Fc_εR(+) cells by IgE was inhibited by rabbit IgG (RGG) or soluble antigen—IgG antibody complexes that have affinity for Fc_γR, but Fc_εR induced in vitro were specific for IgE. The results suggested that the binding of IgE with Fc_γR provided a signal to form and/or express Fc_εR.

A high proportion of Fc_εR(+) cells in the mesenteric lymph nodes from rats infected with Nippostrongylus brasiliensis was maintained if the lymphocytes were cultured in IgE, whereas the proportion markedly diminished if the cells were kept overnight in IgE-free medium. Evidence was obtained that the maintenance in the proportion of Fc_εR(+) cells does not involve recruitment of Fc_γR(+) cells to Fc_εR(+) cells; the proportion of Fc_εR(+) cells in a Fc_γR-depleted fraction was maintained by IgE. Neither RGG nor antigen-IgG antibody complexes affected the maintenance of the Fc_εR(+) cells by IgE. The results collectively suggested that the binding of IgE with either Fc_γR or Fc_εR stimulate lymphocytes to form Fc_εR.