Fig. 5.

HIV-specific cTfh responses increase with initiation of ART and maintain expression of co-inhibitory receptors and a Th1-like phenotype. HIV-specific CD4⁺ responses were analyzed longitudinally using matched PBMC samples obtained during chronic HIV infection (Before ART) or after 1.0–3.2 years of ART (On ART). (a) Net frequency of Ag-specific CD4⁺ responses identified by CD69/CD40L AIM assay or standard IFNγ ICS. (b) Frequency of total (left) or Ag-specific cells with cTfh phenotype (right), defined as CXCR5⁺ memory CD4 T cells. (c) Frequency of Ag-specific CD4⁺ subsets expressing ICOS. (d) Single or co-expression analysis of IRs TIGIT, PD-1 or CD200 on HIV-specific cTfh or non-cTfh before vs after ART initiation. (e) Phenotypic analysis of HIV-specific cTfh (left) or non-cTfh (right) based on the expression of CXCR3 and CCR6 before and after ART initiation. n = 7 longitudinal pairs of untreated/treated HIV-infected donors. Significant p-values are shown in figure and were calculated by Wilcoxon test.