Effect of concanavalin A on the classical complement pathway.
Lysis of sheep erythrocytes (E) sensitized with anti-Forssman antiserum (EA) is inhibited by the action of concanavalin A (Con A) on whole guinea pig complement (GPC). The degree of inhibition observed for a given quantity of GPC was dependent on the Con A concentration. Specifically, Con A inhibits the activity of the early acting complement components C1 and C2 in the fluid phase, but has no significant effect on lysis once these components are bound to EA. Results of tmax experiments performed in the presence or absence of Con A showed that inhibition of C2 activity results from a direct interaction between Con A and C2 and not from a decreased number of effective EAC14 sites. Furthermore, since Con A pretreated or untreated EAC14 cells had the same tmax value, Con A and C2 apparently do not compete for the same binding site on the indicator cells. The lectin has no observable effect on either fluid phase or cell-bound C4 activity. Under similar conditions, wheat germ or soy bean agglutinin, leucoagglutinin or pokeweed mitogen did not inhibit hemolysis.
D000906:Antibodies; D003172:Complement C1; D003175:Complement C2; D003181:Complement C4; D003165:Complement System Proteins; D003208:Concanavalin A / Q000494:pharmacology*; D004912:Erythrocytes / Q000276:immunology; D006461:Hemolysis; D066298:In Vitro Techniques; D037102:Lectins / Q000494:pharmacology
D000906:Antibodies; D003172:Complement C1; D003175:Complement C2; D003181:Complement C4; D037102:Lectins; D003208:Concanavalin A; D003165:Complement System Proteins