A chromogenic assay for evaluation of alpha 2-macroglobulin level in serum and cerebrospinal fluid

A photometric assay using the chromogenic substrate carbobenzoxy-valyl-glycyl-arginine-p-nitroanilide acetate (CHROMOZYM TRY) for the determination of alpha 2-macroglobulin which binds trypsin as a trypsin-protein complex, thus preserving its amidolytic activity, even in the presence of aprotinin, has been studied in serum as well as in cerebrospinal fluid (CSF). Normal range in sera was found to be mean = 10.2 +/- 3.3 kU/l (male), mean = 10.9 +/- 3.2 kU/l (female), and mean = 11.9 +/- 5.0 U/l in CSF. Within-run precision in sera was ascertained to be C.V. = 2.06%, and in CSF C.V. = 2.15%, respectively. There was a good correlation with immunochemical methods: r = 0.974 in 60 sera (p less than 0.001) and r = 0.976 in 16 pathological samples of CSF (p less than 0.001).