Lymphocytes from autoimmune MRL lpr/lpr mice are hyperresponsive to IL-18 and overexpress the IL-18 receptor accessory chain.
MRL lpr/lpr mice spontaneously develop a severe autoimmune lupus syndrome characterized by strong autoantibody production and massive lymphoproliferation, in which IFN-gamma plays a major pathogenic effect. The role of the IFN-gamma-inducing cytokine IL-18 in the autoimmune syndrome of lpr/lpr mice has been investigated. In response to IL-18, lymph node cells of lpr/lpr mice produce significant amounts of IFN-gamma and proliferate more potently as compared with cells from +/+ mice. Cells likely responsible for such hyperresponsiveness to IL-18 include NK cells and the CD4(+)/CD8(+) self-reactive T lymphocytes characteristically present in lymph nodes of lpr/lpr mice. Analysis of the expression of IL-18R complex revealed that mRNA for the IL-18R alpha-chain is constitutively expressed at similar level both in +/+ and lpr/lpr lymphocytes. In contrast, the expression of the accessory receptor chain IL-18R beta is low in unstimulated +/+ cells but significantly high in lpr/lpr cells. Thus, the abnormally high expression of the IL-18R chain IL-18R beta could be one of the causes of the hyperresponsiveness of lpr/lpr cells to IL-18 at the basis of consequent enhancement of IFN-gamma production and development of IFN-gamma-dependent autoimmune pathology.
Dompé Research Center, L'Aquila, Italy.
D
D
Neumann
E
E
Del Giudice
A
A
Ciaramella
D
D
Boraschi
P
P
Bossù
D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D007371:Interferon-gamma / Q000096:biosynthesis; D020382:Interleukin-18 / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D053727:Interleukin-18 Receptor alpha Subunit; D008180:Lupus Erythematosus, Systemic / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008198:Lymph Nodes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D019463:Mice, Inbred MRL lpr; D012333:RNA, Messenger / Q000096:biosynthesis; D018123:Receptors, Interleukin / Q000096:biosynthesis* / Q000235:genetics; D053724:Receptors, Interleukin-18; D013154:Spleen / Q000276:immunology / Q000378:metabolism / Q000473:pathology
C508573:Il18r1 protein, mouse; D020382:Interleukin-18; D053727:Interleukin-18 Receptor alpha Subunit; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053724:Receptors, Interleukin-18; D007371:Interferon-gamma