CCL2 and systemic lupus erythematosus: We evaluated the migratory capacity of circulating monocytes from SLE patients using an in vitro transwell assay, and found that monocytes with elevated FcγRI/CD64 expression exhibited increased migration toward the chemokine MCP-1 (r2 = 0.09, P = 0.005; Spearman's correlation) (Figure 3a).