Anergy in active pulmonary tuberculosis. A comparison between positive and negative reactors and an evaluation of 5 TU and 250 TU skin test doses

Abstract

Based on induration of less than 10 mm at 48 and 72 hours, 49 of 200 (25 percent) patients with active pulmonary tuberculosis failed to respond to intermediate (5TU) strength PPD. Distribution of reactors vs nonreactors was similar with regard to sex but not race, with more white subjects proving to be nonreactive. Additional comparisons between the two groups revealed significantly higher values in the responder population for age, in vitro lymphocyte response to PPD, total serum protein and serum IgG. Responsiveness of lymphocytes to phytohemagglutinin was also increased in this group, but only at lower mitogen concentrations. Alternatively, the nonresponder group demonstrated higher values for alpha-1 globulins. A group of nontuberculous patients similarly subjected to skin testing showed negative reactivity to 5 TU PPD at the much higher incidence of 152/173 (88 percent). The 49 patients with pulmonary tuberculosis and 152 nontuberculous patients who did not respond to 5 TU PPD were further tested with 250 TU PPD. In the group with tuberculosis, 30/49 (61.2 percent) demonstrated positive reactions, whereas only 55/152 (36.2 percent) nontuberculous patients showed induration equal to 10 mm or higher. Skin testing with the recall antigens TOE and SK-SD indicated that only 3/200 (1.5 percent) tuberculous patients could be classified as being anergic; 9/200 (4.5 percent) were specifically anergic to PPD and 7/200 (3.5 percent) demonstrated questionable anergy to PPD as judged by a 250 TU PPD response that was greater than 5 but less than 10 mm.