A specific serine proteinase is inducible in Lyt-2+,L3T4- and Lyt-2-,L3T4+ T cells in vitro but is mainly associated with Lyt-2+,L3T4- effector cells in vivo.
Recently, we and others reported on the expression of a serine proteinase in long-term cultured murine T lymphocyte cell lines. In an attempt to explore the distribution and possible regulation of this enzyme in T lymphocyte subsets, we performed the presented detailed study. We found that the proteinase is not expressed by thymocytes and resting T cells but can be induced by lectin or antigen in combination with lymphokine sources in vitro in macrophage-depleted unselected T cells as well as in both T cell subsets (Lyt-2+,L3T4- and Lyt-2-,L3T4+) separated by flow cytofluorometry. Furthermore, it appears that cell-associated proteinase activity is increasing with prolonged culture period of sensitized T lymphocytes and that it is higher in antigen-activated as compared to lectin-activated T cells. When tested for substrate specificity the T cell-associated proteinase was shown to preferentially cleave model peptide substrates carrying L-arginine at position P1 in combination with nonpolar amino acids at position P2 and P3. As concluded from its sensitivity to proteinase inhibitors the enzyme can be classified as a serine proteinase and by molecular sieving at high ionic strength it was shown to have a mol. mass of approximately 50-60 kDa. Analysis of in vivo activated T cells revealed that this particular proteinase was expressed in flow cytofluorometry sorted lymphocytic choriomeningitis virus-specific Lyt-2+,L3T4- cytolytic T lymphocytes but not in Lyt-2-,L3T4+ T cells presensitized with either Listeria monocytogenes or I-A alloantigens. The data demonstrate that the two T cell subsets (Lyt-2+,L3T4-; Lyt-2-,L3T4+) have distinct in vitro induction requirements for the expression of proteinase and that after activation of T cells in vivo the enzyme is preferentially associated with Lyt-2+,L3T4- effector cells.
D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis*; D002850:Chromatography, Gel; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D010450:Endopeptidases / Q000032:analysis / Q000096:biosynthesis*; D004790:Enzyme Induction; D005434:Flow Cytometry; D007531:Isoflurophate / Q000378:metabolism; D037102:Lectins / Q000494:pharmacology; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D011480:Protease Inhibitors; D012697:Serine Endopeptidases; D013379:Substrate Specificity; D013601:T-Lymphocytes / Q000145:classification / Q000201:enzymology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D037102:Lectins; D008222:Lymphokines; D011480:Protease Inhibitors; D007531:Isoflurophate; D010450:Endopeptidases; D012697:Serine Endopeptidases