AUTOANTIBODIES TO SPECIFIC ENZYMES - A REVIEW

There are two categories of autoantibodies to specific enzymes: immuno globulin-complexed enzymes and circulating autoantibodies directed to enzymes in tissue or tissues. Immunoglobulin-complexed enzymes may res ult in elevated serum enzyme activity. They are found more frequently in elderly patients and have limited clinical significance. Immunoglob ulin association with the enzyme must be demonstrated to distinguish t his macroenzyme from other high molecular weight enzyme complexes. Aut oantibodies to specific enzymes or regulators of enzyme activity do po ssess specific disease associations. The titers or presence of these a utoantibodies may predict morbidity or response to therapy. These auto antibodies may be detected by Western blotting, enzyme-linked immunoso rbent assays, tissue immunofluorescence, radioimmunoassay, immunopreci pitation flow cytometry or inhibition of enzyme activity. For example, anti-pyruvate dehydrogenase inhibits the activity of purified enzyme, but not relatively intact mitochondrial preparations. Most evidence s uggests that the production of autoantibodies to specific enzymes repr esents an epiphenomenon secondary to tissue damage rather than a prima ry event in the pathogenetic pathway.