Regulation of cytokine expression by an autoreactive B cell clone derived from MRL/MP-lpr/lpr mice.
The B cell line, MRL159.5, was established by somatic hybridization between splenic MRL/MP-lpr/lpr (lpr) mice B cells and 2.52M, a hypoxanthine-aminopterine-thymidine (HAT) medium-sensitive B cell line mutant. It possessed a receptor molecule for mouse erythrocytes treated with bromelain (Br-MRBC) on its surface, likely to be an autoreactive B cell clone specific for Br-MRBC as detected by rosette-forming assay with Br-MRBC. MRL159.5 spontaneously produced IL-6 and secreted IgM, and was induced to augment IgM secretion when treated with Br-MRBC or IL-6. Triggering of CD40 led to an augmentation of IgM secretion as well as IL-6 expression. Blocking the binding of IL-6 to its cellular receptor through the use of inhibitory antibodies inhibited CD40-induced IgM secretion, suggesting a possible autocrine role of IL-6 for CD40-induced differentiation of this B cell hybridoma. Addition of IL-4 or Br-MRBC augmented IL-6 expression as well as IgM secretion by CD40-activated MRL159.5 cells. CD40 also augmented tumour necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression but resulted in decreased IL-10 expression. Furthermore, under conditions where IL-6 expression was augmented, IL-6R alpha (gp80) expression was down-regulated, suggesting a negative feedback mechanism of an IL-6 autocrine loop in this hybridoma. These results demonstrate a role by which T cell-dependent activation through CD40 regulates an IL-6 autocrine loop, controlling differentiation of autoreactive B cells in autoimmune disease.
Second Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan.
T
T
Iwasaki
T
T
Hamano
J
J
Fujimoto
A
A
Ogata
E
E
Kakishita
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D001963:Bromelains / Q000494:pharmacology; D019013:CD40 Antigens / Q000378:metabolism; D002460:Cell Line; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis; D006825:Hybridomas; D007075:Immunoglobulin M / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D051379:Mice; D019463:Mice, Inbred MRL lpr; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D019947:Receptors, Interleukin-6 / Q000235:genetics; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000096:biosynthesis; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D000911:Antibodies, Monoclonal; D019013:CD40 Antigens; D016207:Cytokines; D007075:Immunoglobulin M; D015850:Interleukin-6; D011947:Receptors, Antigen, B-Cell; D019947:Receptors, Interleukin-6; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; C113250:interleukin-6 receptor alpha; D016753:Interleukin-10; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D001963:Bromelains