In vivo effects of cyclosporin A: abrogation of the induction of experimental allergic orchitis and sparing of the generation of suppressor cells.

Cyclosporin A (CyA; 10 mg/kg/day) administration for 14 days, starting on the day of immunization with testicular antigen (TA) in complete Freund's adjuvant (CFA), almost completely abrogated the induction of experimental allergic orchitis (EAO), delayed skin reactivities to both TA and purified protein derivative of tuberculin (PPD), and antisperm antibody response in strain 13 guinea pigs when examined 2 weeks after immunization. The unresponsive state induced was of a transitory nature. After cessation of CyA treatment, EAO-eliciting capability and cellular immune responsiveness recovered in relatively short time, while restoration of humoral immune responsiveness was delayed. Transfer of lymph node cells taken from CyA-treated, EAO-suppressed animals at 2 weeks postimmunization into normal syngeneic recipients inhibited the induction of EAO and delayed skin response. The suppressor cell activity appeared to be at least in part antigen-specific. It seems likely, therefore, that the profound suppression of EAO by CyA could be explained as due to the additive effect of the inhibition of helper/inducer T cell generation and the sparing or activation of suppressor cell populations.