A new method for the large scale preparation of antitoxic antibodies exhibiting high specific protective activities.

A method using polyethylene-glycol and immobilized pepsin for purifying heterologous antitoxic antibodies is described. Using horse antitetanus plasma or sera, F(ab')2 fragments exhibiting specific activities in the range of 150 IU per mg protein were repeatedly isolated with a yield around 80%. The procedure was scaled up from 200 ml up to 201.