Prevalence of anti-mycolic acid antibodies in patients with pulmonary tuberculosis co-infected with HIV.

Isolation and purification of mycolic acids from Mycobacterium tuberculosis have allowed them to be applied as antigen in an ELISA-based assay to detect specific antibodies in human sera. Tuberculosis patients have previously been shown to contain antimycolic acids antibodies. The aim of this study was to determine whether human immunodeficiency virus (HIV) co-infection increases false-negative testing rate and whether other random diseases for which hospitalisation is normally required will contribute to false-positive results. Sera from 118 human subjects were tested for the presence of antibodies to mycolic acids; 59 were patients with proven pulmonary tuberculosis and 59 were control hospitalised patients without evidence of tuberculosis. Each group consisted of HIV-seropositive and HIV-seronegative subjects. The endpoint was the detection of specific antibodies to mycolic acids in the sera, before and after precipitation of immune complexes. The two groups of subjects were well matched for age, gender, race and HIV status. On average, humans infected with Mycobacterium tuberculosis showed a specific antibody response to mycolic acids that was not affected by low CD4 T-lymphocyte counts in HIV-seropositive patients but was compromised by various other serious diseases.