MMP9 and systemic lupus erythematosus: At present, DCs are the most powerful antigen presenting cells and the main resource of MDC.13 The functional disorder antigen presenting cells14 and the reduced DCs15 are in existence in patients with SLE has been reported and the proportion of DCs in peripheral blood showed a negative correlation with disease activity.15 From our study it has been shown that serum levels of MDC and MMP-9 were significantly decreased in SLE patients.