Simple method for preparing the cellular intermediate EAC14, and its use for estimation of the second component of complement.

Sensitized erythrocytes carrying the first and fourth components of complement (EAC14) were prepared by incubating optimally sensitized sheep erythrocytes with normal serum appropriately diluted in Mg2+-free diethylbarbiturate buffer containing Ca2+. EAC14 cells so prepared were found to be suitable for use in estimating the second component of complement (C2) in human serum, and the method is described here.