Assessing the specificity of anti-canine-factor VIII-related antigen

Antibodies to canine factor VIII-related antigen should be monospecific to accurately study this protein's location in tissue and its structure. Because no uniformly accepted standard for monospecificity exists for anti-factor VIII-related antigen, we have compared the sensitivities of three common evaluation techniques--immunodiffusion, immunoelectrophoresis, and crossed immunoelectrophoresis. Unabsorbed rabbit anti-canine factor VIII-related antigen appeared monospecific against whole plasma by all three methods; however, multiple specificities were recognized against a plasma cryoconcentrate. These results demonstrate the insensitivity of the techniques under certain conditions, which can lead to erroneous interpretation of data.