Role of C4-binding protein in the defective lysis of sensitized sheep erythrocytes by mouse complement.
Passage of mouse EDTA-plasma over an anti-C4-binding protein (anti-C4-bp) affinity column reduced the C4-bp level by an average of 34% and increased the classical C pathway activity as measured with sensitized normal and desialylated sheep erythrocytes, but not versus sensitized rabbit erythrocytes. This suggests that C-regulation by C4-bp is independent of membrane sialic acid and provides evidence for the presence of a hitherto unknown preferential site for mouse C4-bp on sheep erythrocytes. The absence of both this site and sialic acid on their membranes makes sensitized rabbit erythrocytes useful target cells for assay of mouse classical C pathway activity.
D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification / Q000502:physiology*; D002846:Chromatography, Affinity; D003165:Complement System Proteins / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology*; D016167:Integrin alphaXbeta2; D007525:Isoelectric Focusing; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011817:Rabbits / Q000276:immunology; D012756:Sheep / Q000276:immunology; D012794:Sialic Acids / Q000276:immunology
D002352:Carrier Proteins; D016167:Integrin alphaXbeta2; D012794:Sialic Acids; D003165:Complement System Proteins