Quantification of IL-17F and IL-17A mRNA in CD4 T cells isolated from the blood of SS patients and healthy donors. RNA purified from CD4 T cells freshly isolated from the blood of healthy donors (HD) and patients with SS was subjected to QPCR using primers specific for (A) IL-17A and (B) IL-17F. The expression of IL-17A and IL-17F was normalized to GAPDH, so that the level shown represents copies of IL-17A or IL-17F mRNA per 1000 copies of GAPDH mRNA. Bars denote the average and standard deviation for each skin type analyzed. *Indicates a statistically significant difference (P < .05), whereas NS indicates no significant difference (P > .05).