A method for detecting factor-VIII clotting activity associated with factor VIII-related antigen in agarose gels.

A method for detecting factor-VIII clotting activity in agarose is described. It is based on factor VIII promoting coagulation in a mixture of haemophilic plasma in agarose which is detected by a change in opacity. When this test was used to detect factor-VIII clotting activity in a one-dimensional Laurell electroimmunoassay for factor VIII-related antigen all the factor-VIII activity was found in the same position as the factor VIII-related antigen immunoprecipitate. Factor-VIII clotting activity did not appear to be simply trapped in this immunoprecipitate and therefore it has been concluded that the molecule containing factor-VIII clotting activity carries factor VIII-related antigen determinants.