Inhibition by cyclosporin A of IgE production and cyclophosphamide-induced eosinophilia in rats immunized with non-parasite antigens.

Administration of cyclosporin A (CS-A; 25 mg/kg daily) to rats from the time of immunization with ovalbumin (OVA) in complete Freund's adjuvant abolished the production of anti-OVA antibodies, including IgE. Cyclophosphamide (Cy; 150 mg/kg) given 2 days before immunization also inhibited specific antibody production but at the same time induced a striking eosinophilia. Combined administration of both drugs resulted in the inhibition by CS-A of the Cy-induced eosinophilia. The results suggest that IgE synthesis and eosinophil proliferation may be under the control of separate T cell subsets. This rat model may prove useful in studies on the regulation of eosinophil production and the role of these cells in disease processes.