Booster effect in delayed hypersensitivity skin testing.

After a pilot study had suggested that a drug augmented delayed hypersensitivity, we conducted a control study in which 19 normal volunteers had the same skin test battery applied as in the pilot study, on two occasions one month apart with no intervening treatment. No change was observed in delayed hypersensitivity response to PPD, Candida, or tetanus antigens. However, a significant decrease in response to mumps antigen was observed, and there was a marked "booster" or augmented response to SKSD antigen. These observations have implications for studies of immunomodulation and the mechanism of action of delayed hypersensitivity response.