Mycobacterium tuberculosis specific ELISPOT-based gamma-INF responses in HIV/TB individuals submitted to antituberculosis and HAART regimens including efavirenz
T. Silva1, C.B.W. Giacoia-Gripp2, C.A. Smaltz3, F.M. Sant'Anna4, V. Rolla4, M.G. Morgado2
1Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Laboratory AIDS and Molecular Immunology, Rio de Janeiro, Brazil, 2Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil, 3Oswaldo Cruz Institute, Oswaldo Cruz Foundation Evandro Chagas Clinical Research Institute (FIOCRUZ/RJ), Rio de Janeiro, Brazil, 4Evandro Chagas Clinical Research Institute (FIOCRUZ/RJ), Rio de Janeiro, Brazil
Background: The introduction of HAART reduced mortality and morbidity among HIV patients as well the incidence of new HIV/tuberculosis (HIV/TB) cases. We evaluated the reconstitution of the cellular immune response of HIV/TB individuals with different patters of CD4 counts at study entry, measured by Mycobacterium tuberculosis specific ELISPOT assay along the 6 moths of HIV/TB treatment.
Methods: Eighteen HIV/TB individuals treated with rifampicin and HAART including efavirenz, were recruited at the Evandro Chagas Clinical Research Institute (FIOCRUZ/RJ). Patients were divided in two groups according to the T CD4+ absolute cell counts at baseline visit: < 200 cells/mm3 and > 200 cells/mm3. Based gamma-INF (g-INF) ELISPOT production to PPD, ESAT-6 and 38kDa/CFP antigens were evaluated at different timeline (baseline, D30, D60, D90 and D180).
Results: The proportion of responders for CD4< 200 group to PPD antigen increased from 66% (D1) to 100% at D30 and remained stable until D180. The proportion of responders for CD4>200 group reaches a peak (77%) at D90 and them declined to 55% at D180 during the TB/HIV associated treatment. Very poor responses were obtained for ESAT-6 in both groups. Variable results were obtained for the 38KDa/CFP-10 antigen for both groups but, interestingly, a higher proportion of responders was observed to CD4< 200 one. The magnitudes of the positive responses to tested antigens ranged from 55 to 4230 spots/106 cells in the INF-g ELISPOT based assay.
Conclusions: An apparent immune reconstitution was observed to all patients, since an important and sustained memory response to PPD antigen was detected. Better responses to antigens were observed to the CD4>200 group, according to CD4 levels at TB treatment and HAART submission.
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