Thymus-dependence of autoantibody responses to liver specific lipoprotein in the mouse

Proposed mechanisms for the induction of autoantibodies to liver specific lipoprotein (LSP) assume that the autoantibody response is T-dependent. This hypothesis was tested in the athymic nude mouse. Athymic homozygote (nu/nu) nude mice and appropriate control mouse strains were immunized with rabbit or human LSP and infected with murine cytomegalovirus (MCMV) in an attempt to induce autoantibodies to LSP. Antibodies to LSP were measured by passive haemagglutination and by an enzyme linked immunosorbent assay. Nude mice did not produce antibodies to either foreign LSP species or autoantibodies to mouse LSP when immunized with either rabbit or human LSP. Control heterozygote (nu/+) mice and C57BL/6J mice produced antibody to foreign LSP and autoantibody to mouse LSP when immunized with xenogeneic LSP. Athymic nu/nu mice also failed to produce autoantibody to mouse LSP following infection with MCMV, in contrast to control nu/+ and C57BL/6J mice which produced LSP autoantibody after infection with MCMV. It is concluded that the autoantibody response to LSP is T-dependent.