CX3CR1 and systemic lupus erythematosus: To identify potential biomarkers associated with SLE, we first analyzed a panel of monocyte surface markers, including CD14, Fc receptors (CD16/FcγRIII, CD32/FcγRII, CD64/FcγRI), activation markers (class II MHC, CD62L/L-selectin), and chemokine receptors (CCR2, CX3CR1).