Assay of pertussis vaccine toxicity by a rat-paw-oedema method.

A method is described of using the production of oedema in the foot pad of rats as an index of the ability of pertussis vaccines to cause local reactions. At a suitable time after the subcutaneous injection of the vaccine into hind paw of the rat, the foot is excised and weighed. The technique is reproducible and most useful for the detection of oedema produced by pertussis-vaccine components sensitive to heating at 80 degrees C for 30 min. Substances in pertussis vaccine that produce rat-paw oedema gave maximal reactions at 4 and 12 h. but were best differentiated 9 h after injection.