C3 and systemic lupus erythematosus: It is of some interest that circulating anti-Annexin A1 IgG2 and free Annexin A1 levels are not correlated with each other (Figure 3), nor anti-Annexin A1 IgG2 correlated with serum markers of SLE (i.e., Complement component 3 (C3), Complement component 4 (C4), pathology class, etc.)and with clinical parameters (including SLE activity, corticosteroid doses, etc.); a unique correlation was found between circulating anti-Annexin A1 IgG2 and anti-ds DNA antibodies that are one of the key markers of SLE activity.