Fig 1: Lactate Shapes the Effector Phenotype of CD4+ T Cells at the Site of Inflammation via SLC5A12(A) Relative mRNA expression levels of IL17A, IL22, IFN?, IL6, IL10, and TGFß as assessed by qRT-PCR in tonsil CD4+ T cells treated with sodium lactate (10 mM) and/or SLC5A12 Ab or left untreated (n = 5). Levels of mRNA of each cytokine expressed by lactate-untreated CD4+ T cells were set to 1 (CN, dotted line).(B) IL-17A and IFN? ELISAs from supernatants of tonsil CD4+ T cells treated as in (A), (n = 5, each in duplicate).(C) Relative mRNA expression levels of ROR?T, FOXO1, FOXP3, PD1, CXCR5, and BCL6 as assessed by qRT-PCR in tonsil CD4+ T cells treated as in (A), (n = 5). Levels of mRNA of each cytokine expressed by lactate-untreated CD4+ T cells set to 1 (CN, dotted line).(D) Representative flow cytometry plots of CD4+IL17+, CD4+FOXP3+, CD4+PD1+CXCR5+, CD4+IFN?+, and CD4+IL10+ tonsil CD4+ T cells incubated in the presence or absence of SLC5A12 Ab (left; n = 3). Quantification bar charts (right).(E) Percentage of IFN?+, IL17A+, IL21+, Treg (CD25+Foxp3+), and cytokine-negative (Neg CKS; left) or ROR?t+, Treg (CD25+Foxp3+), Tfh (CXCR5+PD-1+ICOS+), and Tbet+ (right) CD4+SLC5A12+ T cell subsets in 48-h activated human HC PBMCs (n = 5).Two-tailed Student’s t test. Data expressed as mean ± SEM. *p = 0.05; **p = 0.01; ***p = 0.001.