BST2 and systemic lupus erythematosus: Baseline CD317 expression on T cells showed the highest discriminative power in predicting 6-month response, separating responders from non-responders with an AUC of 0.89, surpassing the four-gene IFN gene signature (IFNGS) measured by quantitative PCR (qPCR) (DeLong's test, <i>P</i> = 0.044).<h4>Conclusions</h4>This study demonstrates that higher baseline CD317 expression on T cells is associated with a favorable clinical response to ANI and predicts this response more accurately than the previously proposed IFNGS in patients with SLE.