The effect of a delayed hypersensitivity skin reaction on in vitro parameters of cell-mediated immunity

Immunologic responses following serial skin testing

Twenty volunteers underwent intradermal skin testing with tetanus toxoid (TT) and varicella-zoster (VZ) antigens weekly for 7 weeks. In addition to measurements of delayed hypersensitivity skin test responses, in vitro antigen specific lymphocyte stimulation and antibody levels were monitored. Data for TT exhibited more variability than VZ, demonstrating a marked boost in antibody titers after the first skin test and a shift in the kinetics of the skin test reaction to later maximum responses after the first 3 weeks. In contrast, serial skin testing with VZ was not associated with changes in cellular immune assays. Following the initial VZ skin test there was a slight rise in antibody levels for one-third of studied individuals. These observations suggest that VZ skin test antigen is ideal for monitoring immune function and that repeated testing should not significantly influence in vitro assays.

In vivo and in vitro boosting effects of tuberculin skin tests in guinea-pigs immunized with living BCG or with killed Mycobacterium tuberculosis

Eight weeks after the onset of immunization with living BCG vaccine or with heat-killed, dried Mycobacterium tuberculosis in paraffin oil (TB), guinea-pigs were skin tested with small doses of tuberculin PPD. Three weeks later the effect of these tests on skin reactions and on lymphocyte transformation (LT) responses of lymph node lymphocytes (LNL) or peripheral blood lymphocytes (PBL) was estimated by a comparison with non-tested groups. For both immunogens, the skin test after 8 weeks significantly enhanced skin reactions, particularly to low tuberculin doses. In the BCG-vaccinated guinea-pigs the LT responses of both cell types were significantly enhanced by the skin test after 8 weeks, whereas the LT responses from the TB-immunized guinea-pigs were not affected. Therefore, in the planning and interpretation of in vitro tests of cellular immunity, possible effects from previously applied skin tests should be taken into consideration.