Human granulocyte lysosomal elastase activity using t-butyloxycarbonyl-L-alanine p-nitrophenyl ester and elastin-rhodamine as substrates.

Polymorphonuclear leukocyte lysosomal esterolytic activity on the synthetic substrate, t-butyloxycarbonyl-L-alanine p-nitrophenyl ester was observed to correlate well with polymorphonuclear leukocyte granule elastase activity measured on the natural substrate, elastin, bound to rhodamine. In addition, the effect of highly specific, irreversible chloromethyl ketone elastase inhibitors on leukocyte lysosomal elastase activity was similar, using t-butyloxycarbonyl-L-alanine p-nitrophenyl ester or elastin-rhodamine as substrate. Whether polymorphonuclear leukocyte lysosomal granules contain two different enzymes, a true elastase with esterase activity and a similar esterase without elastase activity, as found in the human pancreas, is, as yet, unknown. Both enzyme activities have been identified in isoenzymes of purified human polymorphonuclear leukocyte lysosomal elastase. The correlations observed between the two enzymes, if present in polymorphonuclear leukocytes, are sufficiently strong to use the esterase assay for clinical purposes.