Complement-mediated solubilization of immune complexes in systemic lupus erythematosus.
The capacity of complement-mediated solubilization of immune complexes (complex releasing activity: CRA) was studied in 63 sera from eight systemic lupus erythematosus (SLE) patients. CRA in sera of active SLE (35 +/- 17.%) was significantly lower than that of inactive SLE (64.1 +/- 24.1%, P less than 0.001). In addition, 20 of 23 sera collected during active diseases demonstrated CRA values less than 50% of the control pooled serum. On the other hand, CRA of 29 of 40 sera from inactive disease exceeded the 50% level. CRA in SLE sera correlated with complement component levels and in particular with the CH50. Serial determination of CRA and of levels of circulating immune complexes (CIC), C4 and C3 in two active patients indicated that the correlation between CRA and the complement components was positive, while that between CRA and CIC was negative. These studies provide evidence that CRA may be useful for following the activity of SLE and that CRA reflects the levels of the complement components of both classical and alternative pathways. The possibility that CIC may be solubilized and opsonized by complement and cleared by the reticuloendothelial system was discussed.
D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000936:Antigen-Antibody Complex / Q000032:analysis / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000276:immunology; D003166:Complement Activating Enzymes / Q000032:analysis; D015922:Complement C1q; D003176:Complement C3 / Q000032:analysis; D003181:Complement C4 / Q000032:analysis; D011415:Complement Factor B / Q000032:analysis; D003165:Complement System Proteins / Q000032:analysis / Q000378:metabolism*; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D011239:Prednisolone / Q000627:therapeutic use; D012995:Solubility
D000305:Adrenal Cortex Hormones; D000936:Antigen-Antibody Complex; D003176:Complement C3; D003181:Complement C4; D015922:Complement C1q; D003165:Complement System Proteins; D011239:Prednisolone; D003166:Complement Activating Enzymes; D011415:Complement Factor B