C3 and systemic lupus erythematosus: It has been found that the expression of ALKBH5 is down-regulated in both PBMCs and T cells of SLE patients, and ALKBH5 mRNA levels are negatively correlated with SLE disease activity index score, erythrocyte sedimentation rate and anti-dsDNA levels, and positively correlated with complement C3 and C4 levels.