TOX mRNA levels are increased in peripheral blood CD4⁺ T cells from SS patients and correlate with disease-specific mortality. (A) TOX mRNA levels in peripheral blood CD4⁺ T cells from SS patients (n = 12), HPs (n = 9), and BID patients (psoriasis [PSO], n = 8; rosacea [ROS], n = 5; vitiligo [VT], n = 5). In each sample, RNA was extracted as described in the “Methods and materials” section. qRT-PCR was performed using primers specific for TOX and GAPDH mRNA. The level of TOX mRNA was normalized to that of GAPDH so that the levels shown represent copies of TOX mRNA per 1000 copies of GAPDH mRNA. (B) TOX mRNA levels in CD4⁺ T cells from SS patients with clonality (n = 7) vs without clonality (n = 5). (C) Receiver operating characteristic curve of TOX mRNA levels in distinguishing SS from non-SS. (D) High TOX mRNA levels in peripheral CD4⁺ T cells correlated with a higher disease-specific mortality. TOX high and TOX low groups were defined by the expression levels higher and lower than 129.9, respectively. AUC, area under the curve.