Monoclonal MOG-reactive autoantibody from progressive EAE has the characteristics of a natural antibody

B-CD8+ T Cell Interactions in the Anti-Idiotypic Response against a Self-Antibody

P3 is a murine, germline, IgM mAb that recognizes N-glycolylated gangliosides and other self-antigens. This antibody is able to induce an anti-idiotypic IgG response and B-T idiotypic cascade, even in the absence of any adjuvant or carrier protein. P3 mAb immunization induces the expression of activation markers in a significant percentage of B-1a cells in vivo. Interestingly, transfer of both B-1a and B-2 to BALB/Xid mice was required to recover anti-P3 IgG response in this model. In fact, P3 mAb activated B-2 cells, in vitro, inducing secretion of IFN-γ and IL-4, although this activation was not detected ex vivo. Interestingly, naïve CD8+ T cells increased the expression of activation markers and IFN-γ secretion in the presence of B-1a cells isolated from P3 mAb-immunized mice, even without in vitro restimulation. In contrast, B-2 cells were able to stimulate CD8+ T cells only if P3 was added in vitro. Using bioinformatics, a MHC class I-binding peptide from P3 VH region was identified. P3 mAb was able to induce a specific CTL response in vivo against cells presenting this peptide. Both humoral and CTL anti-idiotypic responses could be mechanisms to protect against the self-reactive antibody, contributing to keeping the tolerance to self-antigens.

Natural Antibodies as Rheostats for Susceptibility to Chronic Diseases in the Aged

Natural antibodies are spontaneously produced in the absence of infection or immunization, and are both anti-microbial and autoreactive. Autoreactive natural antibodies can bind noxious molecules, such as those involved in clinical situations of atherosclerosis (oxLDL), malignancy (NGcGM3), and neurodegeneration (amyloid, tau) and can affect the fate of their targets or the cells bearing them to maintain homeostasis. Clinically relevant natural antibodies have been shown to decline with advancing age in those few situations where measurements have been made. Consistent with this, human B-1 cells that are thought to be responsible for generating natural antibodies also decline with advancing age. These findings together suggest that an age-related decline in amount or efficacy of homeostatic natural antibodies is associated with relative loss of protection against molecules involved in several diseases whose incidence rises in the older age population, and that those individuals experiencing greatest loss are at greatest risk. In this view, natural antibodies act as rheostats for susceptibility to several age-related diseases. These considerations suggest that administration of natural antibodies, or of factors that maintain B-1 cells and/or enhance production of natural antibodies by B-1 cells, may serve to counteract the onset or progression of age-related chronic illness.

Cross-reactive myelin antibody induces renal pathology

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune model for multiple sclerosis (MS). Previously, we reported renal immunoglobulin (Ig) deposition in mice with myelin oligodendrocyte glycoprotein (MOG(92-106))-induced progressive EAE and naive mice injected with MOG(92-106) hybridoma cells producing antibody that cross-reacts with various autoantigens including double-stranded DNA. To assess whether MOG(92-106) antibodies actually induce kidney changes, the extent of renal Ig deposition and changes in glomerular histology and filtration were investigated. Mice with progressive EAE exhibited Ig deposition, glomerular hypercellularity and proteinuria indicating kidney dysfunction. MOG(92-106) hybridoma cell injected mice also had Ig deposition and proteinuria. Therefore, sensitization with MOG(92-106) and transfer of MOG(92-106) antibodies can induce both central nervous system and renal pathology. The renal involvement reported in MS is believed to occur as a side effect of nephrotoxic drugs or neurogenic bladder. Our results demonstrate that an autoimmune response against myelin could induce pathologic changes in the kidney and may help explain renal changes reported in patients with progressive MS.

Role of CD5+ B-1 cells in EAE pathogenesis

Hybridoma cell lines producing natural autoantibodies (NAA), generated from A.SW mice with progressive experimental autoimmune encephalomyelitis (P-EAE), have been shown to cause demyelination and renal pathology when injected into naive mice. To investigate the relative contribution of these antibodies to disease pathogenesis, B-1 cells, the major producers of NAA, were depleted by hypotonic shock. Depletion of B-1 cells during the effector phase of EAE significantly decreased the severity of demyelination and overall pathology in the brain. There was also a decreased incidence of P-EAE and a decrease in clinical score. Depletion during the induction phase of the disease resulted in an increase in the incidence of P-EAE and in the clinical score. Overall, B-1 cells were found to modulate EAE pathogenesis.

Polyreactive myelin oligodendrocyte glycoprotein antibodies: Implications for systemic autoimmunity in progressive experimental autoimmune encephalomyelitis

Two myelin oligodendrocyte glycoprotein (MOG92-106) monoclonal antibodies (mAbs) were produced from an A.SW mouse with progressive experimental autoimmune encephalomyelitis. Polyreactivity/specificity of the mAbs was demonstrated by ELISA. Functionality and a potential role in pathogenesis of systemic autoimmunity were demonstrated in vitro in a lymphocytotoxicity assay and in vivo upon injection into naïve mice. Injection of MOG mAb producing hybridomas into naïve mice resulted in immunoglobulin deposition in kidneys and liver. This model will be useful in determining whether transitional forms between CNS (organ)-specific and systemic autoimmune diseases exist, and whether progressive multiple sclerosis has features of a systemic autoimmune disease.