Cn. Kennett et al., LOCALIZATION OF ACTIVE AND INACTIVE ELASTASE, ALPHA-1-PROTEINASE INHIBITOR, AND ALPHA-2-MACROGLOBULIN IN HUMAN GINGIVA, Journal of dental research, 74(2), 1995, pp. 667-674
Biochemically, there is usually much less elastase activity in gingiva
l tissue than in crevicular fluid. The tissue distributions of active
and inactive elastase and the endogenous inhibitors alpha-1-proteinase
inhibitor (alpha(1)PI) and alpha-2-macroglobulin (alpha(2)M) were the
refore compared. Inflamed tissue was obtained from chronic periodontit
is patients, and cryostat sections were incubated with the histochemic
al elastase substrate MeOSuc-Ala-Ala-Pro-Val-MNA. Adjacent sections we
re examined immunocytochemically with antibodies to neutrophil elastas
e, alpha(1)PI,alpha(2)M, and leukocyte differentiation antigens. Antig
enic elastase was widely distributed in CD15-positive granulocytes in
both the epithelium and lamina propria as well as in granulomatous tis
sue from infrabony defects. However, there was very limited histochemi
cal staining of these cells, and biochemical activity against the equi
valent substrate MeOSuc-Ala-Ala-Pro-Val-AFC could be extracted only fr
om sections with such staining. The pH optimum and effector response o
f the activity in the extracts were, nevertheless, consistent with tho
se of leukocyte elastase. The large difference between the total elast
ase content of the tissue, as determined immunocytochemically, and the
Limited amount of active enzyme, as demonstrated histochemically, ind
icated that the majority was in an inactive form. The involvement of t
issue inhibitors was suggested by the fact that extracts from sections
with no histochemical staining reduced biochemical elastase activity
in crevicular fluid. alpha(2)M was found in many fibroblasts and also
some CD68-positive macrophages, which additionally contained alpha(1)P
I. Both inhibitors appeared to be present extracellularly, since there
was significant background staining. Thus, alpha(1)PI and alpha(2)M c
ould contribute to the regulation of elastase activity in the gingiva.