A low molecular weight inhibitor of the alternative complement pathway. I. Its isolation from human urine and the reaction mechanism.
A low molecular inhibitor (LMW-INH) of the alternative pathway activation was isolated form healthy human urine. Its molecular weight was slightly higher than 1000. LMW-INH inhibited C3 convertase formation in fluid phase, on sheep erythrocytes and on zymosan particles. In contrast with beta 1H globulin LMW-INH showed no effect on the C3b binding site for B, and it inhibited the activation of CVF.B complex by D only when LMW-INH was simultaneously present with D. These results indicate that the reaction mechanism of LMW-INH is different from that of beta 1H globulin.
D002850:Chromatography, Gel; D003167:Complement Activation; D003176:Complement C3 / Q000037:antagonists & inhibitors; D050577:Complement C3-C5 Convertases / Q000037:antagonists & inhibitors; D003180:Complement C3b Inactivator Proteins / Q000378:metabolism; D017242:Complement Factor H; D003169:Complement Inactivator Proteins / Q000302:isolation & purification* / Q000652:urine; D003170:Complement Pathway, Alternative; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007122:Immunoelectrophoresis
C493495:CFH protein, human; D003176:Complement C3; D003180:Complement C3b Inactivator Proteins; D003169:Complement Inactivator Proteins; C028751:low molecular weight inhibitor (complement); D017242:Complement Factor H; D050577:Complement C3-C5 Convertases