Efficacy of culture filtrate protein preparations from Indian isolates of M. tuberculosis to activate T cells derived from healthy donors.

Setting: While culture filtrate proteins (CFPs) of Mycobacterium tuberculosis appear to be good vaccine candidates for tuberculosis, only CFPs derived from certain popular laboratory strains of M. tuberculosis have been studied for this purpose.
Objective: To compare the relative efficacies of CFP preparations from two laboratory strains and four contemporary clinical isolates of M. tuberculosis to induce T-cell activation.
Design: CFPs were isolated from six strains of M. tuberculosis and were used to induce 1) T-cell proliferation, 2) IFN-gamma secretion, and 3) IL-12 secretion from peripheral blood derived mononuclear cell (PBMC) preparations from 33 healthy donors.
Results: Significant amounts of IL-12 were spontaneously secreted by PBMC preparations; CFP preparations from two clinical isolates (JNU-7 and JNU-51) significantly boosted this response. All six CFP preparations induced IFN-gamma secretion by PBMCs, but those from two contemporary strains of M. tuberculosis (JNU-7 and JNU-22) were most effective in this regard. The effect of CFPs from JNU-7 and JNU-22 was significantly better than those from the laboratory strains (H37Ra and Erdman). Similar results were obtained with the T-cell proliferation parameter.
Conclusion: These results suggest that CFPs derived from selected clinical isolates of M. tuberculosis may outperform those of standard laboratory strains, and may therefore be a better source of potential candidates for a tuberculosis vaccine.