The effects of cyclosporin A on the induction, expression and regulation of the immune response to herpes simplex virus.

Investigations were conducted to determine the effect of cyclosporin A (CsA) on the delayed type hypersensitivity (DTH) and antibody response of mice to Herpes simplex virus (HSV). Given only at the time of priming, the drug had little effect on the subsequent DTH response in mice receiving a 'DTH immunogenic' inoculation regime. However, CsA restored normal responsiveness in groups receiving a 'DTH tolerogenic' regime implying the abrogation of T suppressor (Ts) cells. Ts cell induction was insensitive to cyclophosphamide. Antibody responses were not suppressed after giving CsA with either of these regimes and enhancement was shown in some groups. DTH was substantially reduced by CsA when the drug was given repeatedly between the time of priming and challenge, or when previously primed mice received the drug shortly before challenge.