Fc epsilon R and Fc gamma R expressed on murine IgE-specific suppressor T hybridomas. Dissociation between suppressor activity and Fc epsilon R expression.

Abstract

The expression of Fc receptors specific for IgE (Fc epsilon R) and those for IgG (Fc gamma R) on murine IgE-specific suppressor T hybridomas was studied. While parental T lymphoma cells (BW5147) failed to bind IgE-sensitized red cells (mIgE-TNP-ORBC), the majority of T hybridoma cell lines having IgE-specific suppressor activity contained rosette-forming cells (RFC) binding mIgE-TNP-ORBC (2 to 13% of the total cells). The expression of Fc epsilon R was poor (2% or less) in T hybridoma cell lines without IgE-specific suppressor activity. In addition to Fc epsilon R, IgE-specific suppressor T hybridomas also expressed Fc gamma R as detected by ORBC sensitized with IgG antibodies (EAox gamma). beta-Interferon (IFN) (1,000 to 2,000 U/ml) augmented the expression of Fc gamma R, but not of Fc epsilon R. On the other hand, preculture of the cells with 40 micrograms of mIgE per ml enhanced the expression of Fc epsilon R without augmenting Fc gamma R expression. IgE-specific suppressor activity in the culture supernatants of T hybridomas was also augmented by preculture with mIgE. However, a dissociation between the expression of Fc epsilon R and IgE-suppressor activity was observed. In some of the subclones, mIgE augmented the suppressor activity without inducing the expression of Fc epsilon R. Furthermore, when treated with 5 micrograms of melittin, a phospholipase A2 activator, per ml, IgE-specific suppressor activity of the hybridomas was completely abrogated, whereas IgE-induced expression of Fc epsilon R was enhanced by melittin.