THE PROGNOSTIC UTILITY OF DELAYED-TYPE HYPERSENSITIVITY SKIN TESTING IN THE EVALUATION OF HIV-INFECTED PATIENTS

Many reagents and techniques have been used for delayed-type hypersens itivity (DTH) skin testing in the evaluation of HIV-infected patients, resulting in varied interpretation of the utility of DTH skin testing in this population. We report the development of a simple algorithm f or selection of DTH antigens and the clinical relevance of DTH skin te sting in HIV disease. Antigens and concentrations for testing were fir st evaluated in a demographically matched, HIV-negative, immunological ly healthy population. The testing scheme was then applied to the HIV population of interest for 5 years at several clinical sites. The anti gens and concentrations selected resulted in 100% reactivity to two or more antigens in the HIV-negative cohort. Anergy is thus a distinct i mmunologic abnormality. Although some correlation (r2 = 0.6) of skin t est reactivity and CD4 cell count was found in a cohort of HIV-infecte d individuals, anergy was found to be independently predictive of the development of symptomatic late-stage disease (Walter Reed Stage 6), A IDS, or death. This stepwise evaluation of skin testing and reagents h as led to the modification of the skin testing protocol by defining th e minimum number of antigens required and establishing the independent prognostic role of DTH skin testing in the evaluation of HIV-infected patients. The addition of mumps (40 CFU/ml), tetanus (1:10), and cand ida (1:10) to the purified protein derivative (PPD) skin test provides the critical controls to evaluate the status of PPD skin test in HIV- infected individuals as well as to provide a useful and prognostic cli nical immunology evaluation.