FIG. 2.

Human PBMC respond to recombinant Apa protein by lymphoproliferation and IFN-γ production. (A) The SI values plotted for 30 PPD-positive healthy controls and 22 pulmonary TB patients were derived as a ratio of the counts incorporated by PBMC in the presence of Apa antigen to that observed with unstimulated cells in triplicate cultures. (B, C, and D) IFN-γ production by PBMC from the same group of volunteers shown in panel A in response to the Apa protein, total M. tuberculosis sonicate, and the mitogen PHA, respectively. The horizontal lines specify the mean SI or IFN-γ values observed in each group. P values for significance are shown for each data set. P values of <0.05 are significant. Evidence of age-sex interaction with SI or IFN-γ response to the stimulants within the study groups, treated separately or in concert, did not reach statistical significance (P > 0.05).