Effect of concanavalin A on the functional activity of hemolytic antibody

Concanavalin A (Con A), either in solution or insolubilized by covalent binding to Sepharose 4B, can inhibit the ability of fluid phase 19S, but not 7S, anti-Forssman antibody to sensitize sheep red cells (E) toward lysis by excess guinea pig complement. The efficiency of 19S antibody is unaffected when E are treated with Con A before sensitization or when antibody sensitized cells (EA) are exposed to the lectin before complement is added. Although whole complement activity is retained on a solumn of Con A-Sepharose, cell bound lectin did not act as a complement fixing antibody. Consistent with this result, there was no difference in the amount of C1 fixed by E and E-Con A, or by EA and EA-Con A.