Lack of direct correlation between CD4 T-lymphocyte counts and induration sizes of the tuberculin skin test in human immunodeficiency virus type 1 seropositive patients.

SETTING

The study was conducted in Bobo-Dioulasso, Burkina Faso, where Mycobacterium tuberculosis infection and human immunodeficiency virus type 1 (HIV-1) infection are prevalent.

OBJECTIVE

To identify proportions of representative (test) populations who are reactive to the tuberculin skin test, and to study the relationship between CD4 T-lymphocyte counts and the induration size of the tuberculin skin test in these groups.

DESIGN

A group of 435 healthy students was tuberculin skin tested in order to evaluate the intensity of skin testing in a 'normal' population. The study group consisted of 195 subjects with or without tuberculosis, and with or without HIV-1 infection, who received a tuberculin skin test and a CD4 T lymphocyte count on the same day.

RESULTS

In total, 90% of the control (nontuberculous, HIV negative) subjects, 32% of the HIV-1 seropositive subjects, 76.5% of the tuberculous patients and 57% of the tuberculous HIV-1 seropositive patients were tuberculin positive. There was no direct correlation between the induration size of reactions to the tuberculin skin test and CD4 T-lymphocyte count in these study groups using linear regression analysis.

CONCLUSION

In vivo skin testing using tuberculin yields clinically significant information on the degree of immunodeficiency which is different from that of CD4 T-lymphocyte counts. The tuberculin skin test should therefore be used as an independent marker of the weakened immunological status of HIV-1 seropositive subjects.