title: Tumor immunity in perforin-deficient mice: a role for CD95 (Fas/APO-1).
abstract: CTL and NK cells use two distinct cytocidal pathways: 1) perforin and granzyme based and 2) CD95L/CD95 mediated. The former requires perforin expression by the effectors (CTL or NK), whereas the latter requires CD95 (Fas/APO-1) expression by the target. We have investigated how these two factors contribute to tumor immune surveillance by studying the immunity of perforin-deficient mice against the progressor C57BL/6 Lewis lung carcinoma 3LL, which expresses no CD95 when cultured in vitro. Unexpectedly, the results indicated that the perforin-independent CD95L/CD95 pathway of CTL/NK plays a role in acting against D122 and Kb39.5 (39.5) high and low metastatic sublines, respectively, derived from the 3LL tumor. Although no membrane-bound CD95 was detected on cultured D122 and 39. 5 cells, surface CD95 expression on both D122 and 39.5 was considerably up-regulated when the tumors were grown in vivo. A similarly enhanced expression of CD95 was observed with three additional tumors; LF-, BW, and P815, injected into syngeneic and allogeneic mice. The finding of up-regulated CD95 expression on tumor cells placed in vivo suggests that a CD95-based mechanism plays a role in tumor immunity at early stages of tumor growth. Consequently, the progressive down-regulation of CD95 expression during tumor progression may indeed be an escape mechanism as previously reported. Together, these results suggest a role for CD95-dependent, perforin-independent immunity against certain tumors.
authors.affiliation: Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel; and Department of Surgery "A," Assaf Harofeh Medical Center, Tel-Aviv University, Zerifin, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Rosen
authors.forename: J H
authors.initials: JH
authors.lastname: Li
authors.forename: S
authors.initials: S
authors.lastname: Keidar
authors.forename: I
authors.initials: I
authors.lastname: Markon
authors.forename: R
authors.initials: R
authors.lastname: Orda
authors.forename: G
authors.initials: G
authors.lastname: Berke
mesh_terms: D000818:Animals; D018827:Carcinoma, Lewis Lung / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D007694:Killer Cells, Natural / Q000276:immunology; D008562:Membrane Glycoproteins / Q000172:deficiency* / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D018345:Mice, Knockout; D009368:Neoplasm Transplantation; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology; D019014:fas Receptor / Q000096:biosynthesis / Q000502:physiology*
chemical_list: D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D019014:fas Receptor; D054353:Perforin