Role of inflammatory infiltrate in activation and effector function of cloned islet reactive nonobese diabetic CD8+ T cells: involvement of a nitric oxide-dependent pathway.
To investigate how CD8+ T cells interact with beta cells and local inflammatory cells in islets, we have isolated CD8+ T cell clones from nonobese diabetic (NOD) spleen that recognize and destroy both islets and the NOD insulinoma cell line NIT-1. The clones destroyed NOD islets with pre-existing inflammation better than islets without signs of inflammation. Islets from NOD-scid mice were destroyed only poorly, but that could be improved by adding IL-7 to the assay. Anti-IFN-gamma Abs inhibited destruction of infiltrated islets. Single islets were effective stimulators of IFN-gamma production by cloned CD8+ T cells, which varied >50-fold depending on the degree of islet infiltration. This effect of the islet mononuclear infiltrate could be mimicked by adding spleen cells to NIT-1 cells, which augmented IFN-gamma production above the level stimulated by NIT-1 cells alone. The enhancing effect of spleen cells could be attributed to their macrophage subpopulation and was not MHC restricted, although recognition of islet Ag by cloned CD8+ T cells and subsequent islet destruction was restricted to islets expressing H-2Db molecules. An inhibitor of inducible NO synthase inhibited destruction of inflamed islets by cloned CD8+ T cells. We propose that macrophages in inflamed islets provide a form of bystander costimulation of beta cell-specific CD8+ T cells. CD8+ T cells respond to Ag and costimulation by producing IFN-gamma that activates macrophages. Activated macrophages facilitate islet destruction by CD8+ T cells through a NO synthesis-dependent pathway.
Gurlo
T
T
School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA.
Kawamura
K
K
von Grafenstein
H
H
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002465:Cell Movement; D002999:Clone Cells; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D005260:Female; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007371:Interferon-gamma / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008213:Lymphocyte Activation; D008239:Lysine / Q000031:analogs & derivatives / Q000494:pharmacology; D008264:Macrophages / Q000276:immunology*; D008285:Major Histocompatibility Complex; D051379:Mice; D016688:Mice, Inbred NOD; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II; D015398:Signal Transduction; D013154:Spleen / Q000166:cytology / Q000276:immunology
D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D000949:Histocompatibility Antigens Class II; C090663:N(6)-(1-iminoethyl)lysine; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D008239:Lysine