Th17 cells are preferentially lost from the GI tracts of HIV-infected patients. (A) GI tract and PB lymphocytes from HIV-uninfected persons (○) were stimulated with anti-CD3 in the presence of brefeldin A and stained as in “Intracellular cytokine assay.” GI tract lymphocytes from cohorts of HIV-infected (●) and uninfected persons (○) were stimulated with anti-CD3 overnight (B,D) or with PMA and ionomycin (C,E) for 4 hours in the presence of brefeldin A and stained as in Figure 1. Frequencies of GI tract memory CD4 T cells that produce either IL-17 (A-C) or IFN-γ (D,E) were then measured by flow cytometry. In panels C and E, red symbols signify chronically HIV-infected patients on HAART. (F) Expression of CCR5 by GI tract Th1 and Th17 cells from HIV-infected (●) and HIV-uninfected (○) patients. (G) The frequency of CD13⁺ myelomonocytic cells within total GI tract leukocytes was assessed after gating for CD45 expression with exclusion of dead cells in cohorts of HIV-infected (●) and uninfected persons (○). (H) Expression of IL-23R by memory CD4 T cells in the GI tracts of HIV-infected (●) and HIV-uninfected persons (○).