Potency testing of pertussis immunoglobulins, relationship between neutralisation test and agglutination test

Neutralisation tests were done with pertussis immunoglobulins and immunosera in which mice were immunised by intraperitoneal injection and challenged 4 hours later by intracerebral injection. The results of the neutralisation tests were compared with those of the agglutination tests done with the same preparations. For 2 pertussis immunoglobulins a correlation was found between the results of both tests, but generally no correlation exists between the agglutinating activity and the protective value of the preparations. There is a more than 100-fold difference in their relationship. Therefore a neutralisation test should be used for potency testing of pertussis immunoglobulins.