Ag.pTfh expand following influenza vaccination in VRs.

H1N1 Ag.pTfh cells were identified by flow cytometry after 12 h of PBMC stimulation with H1N1 antigen in influenza-vaccinated young and old HIV+ individuals (red) and HCs (blue) at baseline (T0), day 7 (T1), and day 28 (T2) post vaccination. Ag.pTfh cells were defined as memory (CD45RO+CD27+) CXCR5+CD40L+CD69+ CD4 T cells. (A) Flow cytometry dot plots showing gating strategy for Ag.pTfh cells at T0, T1, and T2 in a young HC VR and VNR. (B) Line graph showing mean frequencies of Ag.pTfh cells for the indicated participant groups. Error bars indicate SEM. (C) Flow cytometry dot plots showing proliferating (CellTracedim) pTfh cells (CD45RO+CD27+CXCR5+CD4+) in young HC VRs and VNRs at T2 following culture with H1N1 antigen (5 d). (D) Line graph showing mean frequencies of CellTracedimpTfh cells for the indicated participant groups with error bars indicating SEM. Statistical analysis was performed to compare study groups and longitudinal analyses using generalized linear mixed models. Horizontal lines indicate significant differences between time points within a group and between groups, and the level of significance corresponds to p-values as follows: *p p p p-Values shown within the graph refer to significant difference between VRs and VNRs at indicated time points. Underlying data used in the generation of this figure can be found in S1 Data. Ag.pTfh, antigen-specific peripheral T follicular helper; CD, cluster of differentiation; CXCR5, CXC chemokine receptor 5; HC, healthy control; O HC, old healthy control; O HIV+, old HIV+; PBMC, peripheral blood mononuclear cell; Unstim, unstimulated cultures; VNR, vaccine nonresponder; VR, vaccine responder; Y HC, young healthy control; Y HIV+, young HIV+.