Levels of complement in sera from inactive SLE patients, although decreased, do not influence in vitro uptake of apoptotic cells

Background: Accumulation of apoptotic cells is considered relevant in the pathogenesis of systemic lupus erythematosus (SLE). Complement factors facilitate the clearance of apoptotic cells and, when decreased, might result in an increased amount of apoptotic cells found in SLE patients.Objective: To determine the influence of complement profiles from inactive SLE patients on the in vitro phagocytosis of apoptotic cells.Methods: Consecutive SLE patients (n = 98) with inactive disease (SLEDAI = 65%, and 20 HC were used in this assay.Results: All HC and 37% of patients had normal complement levels. CH50 level was decreased in 21 % of patients, C3 in 52%, C4 in 29%, Clq in 2% and Clr in 44% of patients. Between patients and HC, differences in level of CH50, C3 and C4 were statistically significant. No difference in phagocytosis index between HC and patients, irrespective of their CH50 level, was detected. No correlation was found between the respective complement levels and phagocytosis index.Conclusion: In most SLE patients with inactive disease, levels of one or more complement components are decreased. However, decreased levels of complement do not result in a significantly reduced in vitro uptake of apoptotic Jurkat cells by MDM. (c) 2005 Elsevier Ltd. All rights reserved.