Figure 2. Down regulation of CD27 on PPD-specific CD4 T cells is associated with active Tuberculosis independent of the HIV status and with progression to active TB in a HIV⁺ seroconverter.

(A) Ratio of IFNγ⁺ CD4 T cells that are CD27⁺ divided by those that are CD27⁻ is shown for 4 different groups of PPD responders delineated by TB disease state and by HIV serology. CD4⁺ T cells were analyzed for each sample using a whole blood intracellular cytokine assay. (B) Histogram analysis of CD27 expression on IFNγ⁺ PPD-specific CD4 T cells (blue line) and total CD4 T cells (black line, grey) over a 15 months period in two subjects who became HIV infected. Subject H19 (upper panel) was diagnosed and treated for active TB 15 months after HIV infection. Subject H228 (lower panel) did not develop TB within three years after HIV infection. Longitudinal analysis of CD27 expression for one subject was determined simultaneously by flow cytometry.