T-cell response to mycobacterial proteins: a comparative study of tuberculous and control immunoblots of Mycobacterium tuberculosis and M. bovis BCG

Abstract

Objective: To evaluate and compare the lymphoproliferative response of human peripheral blood mononuclear cells (PBMC) to fractionated soluble extracts of Mycobacterium tuberculosis H37Rv (MTSE) and M. bovis bacille Calmette-Guérin (BCG) (MBSE), and thereby determine responses that correlate to infection, and to contrast antibody and T-cell responses.

Design: Membrane blots of SDS-PAGE fractionated M. tuberculosis H37Rv and M. bovis BCG were employed for antibody immunoblotting and T-cell proliferative responses using sera and PBMC from seven tuberculous and seven BCG vaccinated control subjects.

Results: The profiles of responses contrasted rather interestingly, with antibody and T-cells responding more to higher and lower molecular weight fractions respectively. T-cells responding to antigens in the 59-88 kDa region discriminated between tuberculous and BCG vaccinated controls (P < 0.05) even though the differences were more toward the 70-75 kDa fractions within the region in question. Responses to smaller molecular weight fractions of both MTSE and MBSE were high in direct contrast to antibody responses. Additionally, responses to MBSE in these regions were generally higher than for MTSE in vaccinated controls. The reverse was the case with tuberculous subjects where responses to MTSE were generally higher, though not sufficiently significant in enough of the tuberculous subjects to be considered discriminatory.

Conclusion: T-cell proliferative responses to mycobacterial antigens in the 59-88 kDa region, and particularly antigens in the 70-75 kDa region, can be an indication of infection with M. tuberculosis, as well as the basis for discriminating between active disease and vaccination with BCG.