Direct immunofixation after isoelectric focusing. An improved method for identification of cerebrospinal fluid and serum proteins.

An improved method for identification of CSF and serum proteins is described, using analytical isoelectric focusing followed by direct immunofixation in polyacrylamide gel. This method offers high sensitivity together with retained resolution after isoelectric focusing and is technically easy to perform. The gamma-trace protein, normal transferrin, haptoglobin and alpha 2-macroglobulin and two genetic alterations of transferrin were analyzed. The qualitative differences, previously observed on crossed immunoelectrofocusing, between transferrin and alpha 2-macroglobulin in the CSF and serum were confirmed by immunofixation. Protein components, differing in isoelectric pH by at least 0.03 pH unit and 0.5 mm apart were readily identified by this technique.