Diphtheria-tetanus skin testing. Its clinical value for delayed hypersensitivity.

Skin testing as an in vivo means of evaluating cell-mediated immune function is extremely valuable. However, problems lie in selecting the appropriate antigens and interpreting the results. The suggestion that diphtheria-tetanus would provide a good antigen in infants and children was evaluated by comparing skin test observations with results of skin biopsy examinations. Thirteen subjects, seven of whom were immunodeficient, were evaluated by skin reactions and dermal biopsy specimens. Fifty percent of the immunodeficient patients had positive skin test reactions but had biopsy specimens that were not consistent with delayed-type hypersensitivity (DTH). Although all normal controls on whom biopsies were done had histologic DTH reactions, two had negative or equivocal skin reactions. Our data suggest, on the contrary, that delayed hypersensitivity testing with this antigen is not a good screening test for disorders of immunity or inflammation.