Screening test for alpha 1-antitrypsin in dried-blood specimens.

We describe a fluorescent spot test for detecting alpha 1-antitrypsin activity in dried-blood specimens. The eluate of a blood disc is mixed with carbobenzoxy-L-arginine-7-amino-4-methylcoumarin amide and trypsin at the appropriate pH. In the absence of alpha 1-antitrypsin, aminomethylcoumarin, a strongly fluorescent compound, is released. The reaction mixture, when spotted on chromatography paper and viewed under ultraviolet light, exhibits a bright fluorescence only in the case of specimens with alpha 1-antitrypsin deficiency. alpha 1-Antitrypsin activity so estimated correlated well with quantitative assays of dried-blood spots and serum. The procedure is simple and inexpensive, and has the potential for use as a screening test.