Concentration dependent functional responsiveness to subcellular antigenic extracts of BCG and different mycobacterial PPDs, of tuberculin (Mtb-PPD) reactive human T-cell lines.

Abstract M. tuberculosis purified protein derivative (Mtb-PPD) as tuberculin, other mycobacterial PPD-preparations and subcellular antigenic extracts of BCG showed varying concentration dependent bimodal effects in lymphoproliferative assay (LA) of Mtb-PPD generated human CD4+ T-cell lines (TCLS). Inhibitory effect on LA by high dose of Mtb-PPD is correlated with the inhibition of IL-2 production during the antigen induced stimulation. Consequently, maximal and inhibitory concentrations of different antigens in dose response LA varied for different TCLS. However, inhibitory effect can be overcome by the high concentration of non inhibitory antigen for the particular TCL. These results indicate that i) dose dependent LA is essential for the evaluation of antigen specificity of TCL; ii) some mycobacterial antigen may induce anergy of certain concentration whereas some others exert positive effect to overcome such anergy related to inhibition or production of IL-2.