Nongranular proteolytic enzymes of rat IL-2-activated natural killer cells. I. Subcellular localization and functional role.
Our investigations indicate that a variety of neutral serine proteases exist in highly purified, IL-2-activated rat NK (A-NK) cells. These enzymatic activities are not restricted to only cytolysin-containing granules and are not defined by only the assay of N-alpha-benzyloxycarbonyl-L-lysine thiobenzylesterase activity. These activities, which we term A-NKP 1, A-NKP 2, A-NKP 3, and A-NKP 4, cleave, respectively, the following fluorogenic peptide substrates: Boc-Phe-Ser-Arg-7-amino-4-methylcoumarin (AMC, trypsin-like); Suc-Ala-Ala-Phe AMC (chymotrypsin-like); Suc-Gly-Pro-Leu-Gly-Pro AMC (collagenase-like), and Z-Phe-Arg AMC (another trypsin-like enzyme). The proteases A-NKP 1, A-NKP 2, and A-NKP 3 are not cell surface-associated and appear to be cytosolic as defined by isopycnic sucrose density gradient centrifugation. In contrast, A-NKP 4 appears to be located in lysosomes. Treatment of rat A-NK cells with protease inhibitors that inhibit A-NKP 2 and A-NKP 3 also substantially inhibit A-NK cell-mediated cytotoxicity against both NK-sensitive and -resistant targets (YAC-1 and P815, respectively). These results indicate that A-NKP2 and A-NKP 3 may play a role in IL-2-activated NK cell-mediated cytotoxicity. A variety of proteolytic enzymes, in addition to granzymes, therefore exist in A-NK cells. Our studies indicate that a prerequisite to a thorough understanding of the role of proteases in killer cell function is the investigation of several classes of enzymes in addition to granzymes contained in lytic granules.
Goldfarb
R H
RH
Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, PA 15213.
Wasserman
K
K
Herberman
R B
RB
Kitson
R P
RP
D000818:Animals; D002451:Cell Compartmentation; D003602:Cytotoxicity, Immunologic; D007111:Immunity, Cellular; D007376:Interleukin-2 / Q000494:pharmacology; D015979:Killer Cells, Lymphokine-Activated / Q000201:enzymology* / Q000648:ultrastructure; D007694:Killer Cells, Natural / Q000201:enzymology; D008297:Male; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344
D007376:Interleukin-2; D011480:Protease Inhibitors