Preparation of stable erythrocyte target cells suitable for detection of the antibody response to the haptens azobenzenearsonate, azophenyltrimethylammonium and azophenylphosphorylcholine by plaque-forming cell assay.

The preparation of sheep red blood cells (SRBC) which have been sensitized with the haptens azobenzenearsonate, phosphorylcholine and azophenyltrimethylammonium, and are suitable for use in a plaque-forming cell assay, is described. Each hapten is first coupled to a phenolic imidoester (methyl-p-hydroxybenzimidate) and the substituted imidoesters are employed to prepare target SRBC. Details are presented concerning synthesis and purification of the imidoesters, as well as conditions for coupling to SRBC. The hapten-SRBC prepared by this method are very stable and offer significant advantages over other procedures for coupling these haptens to red blood cells.