Stabilization of the classical pathway C3 convertase C42, by a factor F-42, isolated from serum of patients with systemic lupus erythematosus.
Sera from sixteen patients with SLE were investigated for the presence of a factor which would conserve convertase activity on preformed EAClgp 4hu2hu for 30 min at 30 degrees in EDTA. Although such a factor could not be detected readily in the sera, chromatography on DE-52 cellulose yielded fractions appearing as three peaks in one patient and as two peaks in a second patient. These peaks were capable of conserving C42 activity and were designated as F-42. Purification of F-42 from the second peak eluting between 4 and 7 mS on DE-52 was obtained by SP-C50, S-300 and QAE-A50 chromatography. F-42 exhibited charge heterogeneity upon SP-C50 chromatography. On polyacrylamide gel electrophoresis the final material migrated as one band, which coincided with the position of F-42 activity upon eluation from a parallel gel. F-42 had an apparent molecular weight of 150,000 and reacted with anti-IgG in Ouchterlony analysis. Sepharose-bound anti-IgG was capable of neutralizing F-42 activity. The purified material was shown to prolong the half-life (T 1/2) of performed cell-bound C42 in GVB-EDTA at 30 degrees from 5 to 80 min.
D000906:Antibodies / Q000302:isolation & purification* / Q000378:metabolism; D003166:Complement Activating Enzymes / Q000378:metabolism*; D050577:Complement C3-C5 Convertases / Q000378:metabolism*; D003171:Complement Pathway, Classical; D004306:Dose-Response Relationship, Immunologic; D006207:Half-Life; D006461:Hemolysis; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008970:Molecular Weight
D000906:Antibodies; C027314:Factor-42; D007074:Immunoglobulin G; D003166:Complement Activating Enzymes; D050577:Complement C3-C5 Convertases