Identification of human immunodeficiency virus-infected individuals by delayed type hypersensitivity skin testing

OBJECTIVE: To determine if more useful information could be derived from delayed type hypersensitivity skin testing of human immunodeficiency virus (HIV)-infected patients by measuring the amount of induration in response to skin testing in contrast to assessing for the presence of anergy. DESIGN: Prospective, double-blind trial. SETTING: Two HIV clinics. PATIENTS: A sample of 60 ambulatory, HIV-infected patients and 18 normal controls. INTERVENTIONS: Delayed type hypersensitivity skin testing with a panel of recall antigens. MAIN OUTCOME MEASURES: Anergy, total induration in response to the panel of antigens, and CD4 lymphocyte count. RESULTS: Anergy was present in only 28 of 60 (46.7 percent) HIV-infected subjects. A low skin test score (under 20 mm of total induration) was present in 43 of 60 (71.7 percent) HIV-infected subjects (p < 0.01 vs anergy). One control patient was anergic, while two had a low skin test score (p = NS). Among HIV-infected subjects, there was poor correlation between CD4 lymphocyte count and skin test score (R2 = 0.12). CONCLUSIONS: Skin testing by this method identifies more HIV-infected patients than does assessing the presence or absence of anergy.