ANTI-A60 IMMUNOGLOBULIN-G IN THE SERODIAGNOSIS OF TUBERCULOSIS IN HIV-SEROPOSITIVE AND SERONEGATIVE PATIENTS

Objective: A60 is a high molecular weight mycobacterial antigen comple x. The detection of immunoglobulin (Ig) G antibodies to A60 has been a dvocated as a reasonably sensitive and specific test for active tuberc ulosis (TB). We aimed to compare the sensitivity of this test among HI V-seropositive and HIV-seronegative patients with pulmonary TB. Method s: The presence and concentration of anti-A60 IgG antibodies was asses sed by enzyme-linked immunosorbent assay in 208 HIV-seropositive and 9 1 HIV-seronegative Zairian patients with smear-positive pulmonary TB. The relationship between anti-A60 IgG levels and HIV serostatus, CD4lymphocyte counts, presence of clinical AIDS, and tuberculin skin test results was verified. Results: Only 36.5% of the HIV-seropositive, co mpared with 69.2% of the HIV-seronegative patients had a positive anti -A60 IgG test (P <0.00001). Among HIV-seropositive patients, anti-A60 Ige levels did not differ according to CD4+ lymphocyte counts, presenc e of clinical AIDS, or tuberculin skin test results. Conclusions: Amon g patients with pulmonary TB, the sensitivity of testing for anti-A60 IgG was much lower among HIV-seropositive than among HIV-seronegative patients, even from the early stages of HIV-related immunodeficiency. This limits the utility of anti-A60 IgG-antibody testing in the diagno sis of TB among HIV-infected patients.