Tuberculin skin test and CD4+/CD8+ T cell counts in adults infected with the human immunodeficiency virus in Medellín, Colombia.

To evaluate the effect of BCG vaccination and T lymphocyte subpopulations on the reactivity to the tuberculin skin test, 113 asymptomatic HIV+ individuals were tuberculin tested by intradermal injection of 5TU of purified protein derivative and the levels of circulating lymphocyte (CD3, CD4 and CD8) subpopulations determined by indirect immunofluorescence. Ninety-two percent of the subjects included in the study were males. The mean age of the group was 32.1 +/- 7.4 years. Sixty-two percent presented a BCG scar. However, only 22% exhibited positive tuberculin reactions (> or = 5 mm) irrespective of the presence of the BCG scar. Tuberculin positive individuals exhibited higher CD4+ cell counts (p = 0.004) and CD4+/CD8+ ratios (p = 0.006) than tuberculin negative (< 5 mm) HIV+ individuals. The number of individuals with positive tuberculin reactions was significantly higher in subjects with more than 500 CD4+ lymphocytes/microliter (p = 0.02) or CD4+/CD8+ ratios > or = 1.12 (p = 0.002). These results suggest that a prior BCG vaccination does not influence the reactivity to the tuberculin skin test in HIV+ asymptomatic individuals and that the number of CD4+ lymphocytes and the CD4+/ CD8+ ratio positively correlate with the tuberculin reactivity.