The aim of the present study was to evaluate serum and lymphocytic levels of NGF, BDNF and NT-3 in SLE patients and identify their relation to clinical features (systemic activity assessed by SLEDAI score, joint, skin, neurological and kidney involvement, vasculitis), SLE-related immunological activity (anti-native DNA antibodies, complement activation via CH 50, C3 and C4 levels), and anti-phospholipid antibodies. The gene discussed is C4A; the disease is systemic lupus erythematosus.