title: Homeostatic regulation of CD8+ T cells by perforin.
abstract: To prevent uncontrolled expansion, the massive proliferation of T cells during an acute immune response has to be followed by controlled deletion. Here we show that similar to Fas, perforin is not only an important effector molecule of cytotoxic T lymphocytes (CTL) but also involved in down-regulating peripheral T cells. Mice deficient for both the CTL effector molecule perforin and the apoptosis-inducing Fas ligand spontaneously develop infiltration of highly activated CD8(+) T cells in kidney and liver and die between 5 and 12 weeks of age. Injection of staphylococcal enterotoxin B (SEB) into perforin-deficient mice results in dramatically increased selective expansion and prolonged persistence of CD8(+), but not CD4(+), SEB-reactive T cells. Also, secondary immunization of TCR transgenic perforin-deficient mice with the lymphocytic choriomeningitis virus glycoprotein-derived epitope peptide leads to an increased proliferation of transgenic CD8(+) T cells, that is not explained by failure to deplete professional antigen-presenting cells. These results point to a novel mechanism of T cell homeostasis in which the acquisition of perforin-dependent cytotoxic activity regulates the expansion and persistence of CD8(+) effector T cells in vivo.
authors.affiliation: Ontario Cancer Institute/Amgen Institute Toronto, Canada. dkagi@amgen.com
authors.forename: D
authors.initials: D
authors.lastname: Kägi
authors.forename: B
authors.initials: B
authors.lastname: Odermatt
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
mesh_terms: D000818:Animals; D000956:Antigens, Viral; D015704:CD4 Antigens / Q000096:biosynthesis; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000821:virology; D015536:Down-Regulation / Q000276:immunology; D006023:Glycoproteins / Q000008:administration & dosage / Q000276:immunology; D006706:Homeostasis / Q000276:immunology*; D007275:Injections, Intravenous; D008213:Lymphocyte Activation / Q000276:immunology; D008216:Lymphocytic Choriomeningitis / Q000276:immunology; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000008:administration & dosage / Q000276:immunology; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D018089:Superantigens / Q000008:administration & dosage; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014764:Viral Proteins
chemical_list: D000956:Antigens, Viral; D015704:CD4 Antigens; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D052899:Pore Forming Cytotoxic Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018089:Superantigens; C075784:T cell receptor Vbeta8; D014764:Viral Proteins; C094244:glycoprotein peptide 33-41, Lymphocytic choriomeningitis virus; D054353:Perforin