Improved electroimmunoassay of factor VIII-related antigen.

Factor VIII-related antigen migrates poorly into gel during electrophoresis in agarose, probably in major part because of the relatively high sulfate content of the commonly used agars. A recently available low-sulfate residue agar, substituted for standard agar preparations in electroimmunoassay, allows Factor VIII antigen to travel more rapidly, producing "rockets" that are well defined and easily measured, making the assay easier and more reliable.