Evaluation of IgG, IgM, and IgA antibodies to Mycoplasma penetrans detected by ELISA and immunoblot in HIV-1-infected and STD patients, in Sao Paulo,Brazil

The aim of the present study was to determine the frequency of IgG, IgA, an d IgM antibodies to Mycoplasma penetrans in HIV-1-infected patients and in patients with sexually transmitted diseases. We tested serum samples from 1 06 HIV-1-positive patients and 110 individuals with clinical symptoms of ur ethritis. ELISA and the immunoblot test were performed using M. penetrans l ipid associated membrane proteins as antigen. By ELISA, we found a higher f requency (P < 0.05) of IgG against M. penetrans in HIV-1-infected and STD p atients (25.5 and 17.3%) than in controls (1.2%), as well as a higher frequ ency of IgA (P < 0.05) (15.1 and 17.3% compared to 1.2%). For IgM, no diffe rences were observed (P greater than or equal to 0.05) (3.8, 9.1, and 5.8%, respectively). When the frequencies of IgG, IgM, and IgA antibodies of the HIV-1-infected patients were compared taking into account the CD4/CD8 cell ratios < 0.3 and greater than or equal to 0.3, no significant differences were observed between the two groups (13.3, 10, and 20%, compared to 20, 0, and 5%, respectively) (P > 0.05), possibly due to the low number of sample s on which we could perform T-cell counts (53/106). The M. penetrans peptid e of 38 kDa, considered immunodominant, was recognized in immunoblot by 51. 8% of positive sera by ELISA for IgG, 50.0% for IgM, and 75% for IgA in the AIDS patients group, and by 47.4, 60.0, and 75.0%, respectively, in the se xually transmitted disease group. Cross-reactions in immunoblot for IgG wer e observed in sera from individuals infected with Mycoplasma pneumoniae and Mycoplasma hominis, and cross-reactions in immunoblot for IgA were observe d in sera from individuals infected with M. hominis; all of them were ELISA negative to M. penetrans. (C) 1999 Editions scientifiques et medicales Els evier SAS.