Tuberculin skin test and CD+4/CD8+ T cell counts in adults infected with the human immunodeficiency virus in Medellin, Colombia

ABSTRACT

To evaluate the effect of BCG vaccination and T lymphocyte subpopulations on the reactivity to the tuberculin skin test, 113 asymtomatic HIV+ individuals were tuberculin tested by intradermal injection of 5TU of purified protein derivate and the levels of circulating lymphocyte (CD3, CD4 and CD8) subpopulations determined by indirect immunoflurescence. Ninety-two per cent of the subjects included in the study, were males. The mean age of the group was 32.1ñ7.4 years. Sixty-two percent presented a BCG scar. However, only 22 per cent exhibited positive tuberculin reations (ò5mm) 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 (<5mm) HIV+ individuals. The number of individuals with positive tuberculin reactions was significantly higher in subjects with more than 500 CD4+ lymphocytes/µl (p=0.02) or CD4+/CD8+ ratios ò1.12 (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+ lymphocytes and the CD4+/CD8+ ratio positively correlate with the tuberculin reactivity.