Formation of IgE-binding factors by rat T lymphocytes. I. Induction of IgE-binding factors by poly I:C and interferon.

Abstract

Abstract Rat serum obtained 8 to 18 hr after an i.p. injection of poly l:C contained IgE-binding factors, which can be detected by the inhibiton of rosette formation of FcϵR(+) cells with IgE-coated erythrocytes. Incubation of normal rat spleen cells with 1 µg/ml poly l:C resulted in the formation of IgE-binding factors. Approximately one-half of the IgE-binding factors in the culture supernatant were IgE-potentiating factors, which have affinity for concanavalin A (Con A), whereas the remaining half of the factors were IgE-suppressive factors with no affinity for the lectin. Culture supernatants of poly l:C-stimulated spleen cells as well as the serum of poly l:C treated rats contained not only IgE-binding factors but also soluble factors that induce normal lymphocytes to form IgE-binding factors. It was found that poly l:C-stimulated splenic adherent cells and peritoneal macrophages formed soluble factors, which in turn induced T lymphocytes to express FcϵR and to form IgE-binding factors. The inducers derived from poly l:C-stimulated cells failed to augment the expression of FcϵR on B cells. The soluble factors could induce the formation of both IgE-potentiating factors and IgE-suppressive factors. Upon incubation with the inducers, 10 µg/ml Con A-activated cells formed IgE-potentiating factors; 1 µg/ml Con A-activated cells formed IgE-suppressive factors. The inducers had affinity for polyuridylic acid and blue dextran Sepharose, and could be recovered from the beads by elution with 1 M NaCI. It was also found that supernatant of mouse spleen cells co-cultured with virus-infected Hela cells induced normal rat lymphocytes to form IgE-binding factors. The inducers in the culture supernatants were neutralized by a minute dose of antibodies specific for mouse type I interferon, indicating that mouse interferon can induce the formation of IgE-binding factors.