CTLA4 and tuberculosis: Although there were no significant differences in the frequency of CD4 T cell subsets expressing each combination of BTLA, CTLA-4, and PD-1 between HIV-infected and HIV-uninfected individuals (Figures 2A,B), we did observe significant differences in the overall total number of inhibitory receptors expressed by CD4 T cells in individuals with LTBI and active TB (Figure 2C).