Plasma anti-proteases in Duchenne muscular dystrophy

Abstract

A comparative study of total antiproteolytic capacity of plasma from 9 boys with Duchenne muscular dystrophy and 10 age-matched controls showed a higher average value in the dystrophic group. Rocket immunoelectrophoretic analysis showed that, although the levels of the major antiprotease α 1-antitrypsin were normal in the dystrophic group, the levels of α 1-macroglobulin were substantially elevated. Comparison with a separate control group showed that this elevation was highly significant. Given recent indications of the importance of elevated muscle lysosomal protease activity in the maintenance of the high rate of muscle protein breakdown in dystrophics, coupled with the demonstration that α 2-macroglobulin is the most important plasma inhibitor of one such protease, cathepsin B 1; this finding raises the possibility that elevation of α 2-macroglobulin levels in dystrophics may be a control mechanism by which the body attempts to restore balance to the aberrant muscle protein catabolism.