title: T-B collaboration for autoantibody production in lpr mice is cognate and MHC-restricted.
abstract: A central question in autoimmunity is the mechanism of T cell help for autoantibody production. For responses to exogenous Ag, T-B collaboration is restricted by MHC class II molecules. To determine whether T cell help that leads to autoantibodies in murine SLE is also MHC-restricted, we have constructed bone marrow chimeras with Ig heavy chain (lgh) allotype- and I-A-congenic donor B6/lpr mice and I-A-congenic recipients. Developing T cells were thus positively selected in the host thymus to interact with B cells bearing I-A of one haplotype or the other. Additional control host mice were heterozygous for I-A expression, allowing T helper cell selection for both I-A haplotypes. Five months after reconstitution, serum total IgG2a, IgM, IgG2a antichromatin, and IgM rheumatoid factor were quantitated by allotype-specific ELISA. Data showed that whereas substantial numbers of B cells were present from both donor strains in all mice, autoantibody production was overwhelmingly from those donor B cells expressing the same I-A haplotype as the host. Sera from the I-A heterozygous control recipient group had roughly equal quantities of autoantibodies of both allotypes, as expected. The finding of MHC class II restriction implies that the T cell help that drives autoantibody production in lpr mice is delivered through cognate (cell-to-cell) interactions and not by soluble factors alone.
authors.affiliation: Department of Medicine, University of North Carolina, Chapel Hill 27599.
authors.forename: E S
authors.initials: ES
authors.lastname: Sobel
authors.forename: V N
authors.initials: VN
authors.lastname: Kakkanaiah
authors.forename: M
authors.initials: M
authors.lastname: Kakkanaiah
authors.forename: R L
authors.initials: RL
authors.lastname: Cheek
authors.forename: P L
authors.initials: PL
authors.lastname: Cohen
authors.forename: R A
authors.initials: RA
authors.lastname: Eisenberg
mesh_terms: D000818:Animals; D001323:Autoantibodies / Q000096:biosynthesis*; D015551:Autoimmunity; D001402:B-Lymphocytes / Q000276:immunology; D002450:Cell Communication / Q000276:immunology; D002678:Chimera / Q000276:immunology; D004195:Disease Models, Animal; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D007126:Immunoglobulin Allotypes / Q000096:biosynthesis; D008180:Lupus Erythematosus, Systemic / Q000235:genetics / Q000276:immunology*; D008211:Lymphocyte Cooperation / Q000276:immunology*; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D001323:Autoantibodies; D000949:Histocompatibility Antigens Class II; D007126:Immunoglobulin Allotypes