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The complement system is profoundly involved in the pathogenesis of acetylcholine receptor (AChR) antibody (Ab) related myasthenia gravis (MG) and its animal model experimental autoimmune myasthenia gravis (EAMG). The most characteristic finding of muscle pathology in both MG and EAMG is the abundance of IgG and complement deposits at the nerve-muscle junction (NMJ), suggesting that AChR-Ab induces muscle weakness by complement pathway activation and consequent membrane attack complex (MAC) formation. This assumption has been supported with EAMG resistance of complement factor C3 knockout (KO), C4 KO and C5 deficient mice and amelioration of EAMG symptoms following treatment with complement inhibitors such as cobra venom factor, soluble complement receptor 1, anti-C1q, anti-C5 and anti-C6 Abs. Moreover, the complement inhibitor decay accelerating factor (DAF) KO mice exhibit increased susceptibility to EAMG. These findings have brought forward improvisation of novel therapy methods based on inhibition of classical and common complement pathways in MG treatment., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In myasthenia gravis (MG), the neuromuscular transmission is impaired by antibodies (Abs) specific for muscle acetylcholine receptor (AChR). Anti-AChR Abs can be detected in the serum of MG patients, although their levels do not correlate with disease severity. In this study, we developed a flow cytometric assay for the detection of peripheral blood AChR-specific B cells to characterize B cell phenotypes associated with experimental autoimmune myasthenia gravis (EAMG). Alexa-conjugated AChR was used as a probe for AChR-specific B cells (B220+Ig+). Mice with EAMG had significantly elevated frequencies of AChR-specific IgG2+ and IgM+ B cells. While the frequencies of IgG2+ B cells and plasma anti-AChR IgG2 levels significantly correlated with the clinical grades of EAMG, the frequencies of IgM+ B cells and plasma anti-AChR IgM levels did not. These results indicate that the frequency of AChR-specific and IgG1+ (mouse IgG2 equivalent) peripheral blood B cells and anti-AChR IgG1 levels could be potential biomarkers for MG disease severity., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Gene(s) at the I-A subregion of the murine major histocompatibility complex influence susceptibility to experimental autoimmune myasthenia gravis. C57Bl/6 mice immunized with acetylcholine receptors (AChR) in complete Freund's adjuvant demonstrated cellular and humoral immune responses to AChR. They developed muscle weakness characteristic of myasthenia gravis and demonstrated a reduction in the muscle AChR content. The kinetics of AChR-specific lymphocyte proliferation generally correlate with anti-AChR antibody response. AChR-specific lymphocyte proliferation was also observed in C57Bl/6 splenocytes after secondary immunization with AChR. The in vitro cellular reactivity to AChR in experimental autoimmune myasthenia gravis (EAMG) mice (C57Bl/6) was suppressed by monoclonal anti-I-Ab antibodies directed against private (Ia20) or public (Ia8) specificities, suggesting a critical role for these Ia determinants in the cellular immune response to AChR in murine EAMG.

Genes in the major histocompatibility complex (H-2) of the mouse control several immune functions as well as various facets of testosterone (Te) physiology. In order to study the genetic control of Te-induced immune suppression, complete Freund's adjuvant (CFA; containing Mycobacteria tuberculosis) was administered parenterally to several mouse strains differing at the H-2 complex which were either sham- or Te-treated. The specific lymphocyte proliferative response to purified protein derivative (PPD) was measured in draining lymph node cells. The response to PPD in strains bearing H-2b (B6 and B10) but not H-2d (B10.D2 and DBA/2) or H-2k (B10.BR and AKR) haplotypes was markedly lower in Te-implanted compared to sham-implanted controls. This result suggests that the ability of Te to dampen the immune response to PPD is regulated by H-2-linked gene(s).

Calorie restriction is known to preserve the immunologic function and prolong the life span of autoimmune-susceptible mice. In order to determine the influence of calorie restriction on cellular and humoral immunity, we tested lymphocyte proliferative response and antibody response to T-dependent antigens in C57Bl/6 mice maintained on restricted diets. C57Bl/6 mice fed a low-calorie diet demonstrated a marked reduction in T-dependent-antigen-specific lymphocyte proliferation and antibody response when compared to mice fed ad libitum. The depressed lymphocyte response seen in calorie-restricted animals is attributed to a defect in both the macrophages and T cells in antigen processing, presentation, and/or proliferation.

T-Lymphocyte number and functions are often reduced, while B-lymphocyte function is often increased in patients with autoimmune disorders. To study the mechanisms responsible for these T-cell malfunctions in autoimmunity we adapted the murine experimental autoimmune myasthenia gravis (EAMG) model. Splenocytes from C57BL/6 mice immunized with acetylcholine receptors (AChR) in complete Freund's adjuvant (CFA) produced approximately half the amount of concanavalin A (Con A)-induced interleukin 2 (IL-2) as did splenocytes of CFA-inoculated controls. Further, AChR plus CFA-immunized splenocytes showed a marked reduction in T-cell proliferative responses induced by Con A or phytohemagglutinin when compared with CFA-inoculated controls. By contrast, lipopolysaccharide-induced B-cell function is preserved. Deficient Con A splenic T-cell response is seen early after secondary inoculation with CFA or AChR in CFA. T-Cell recovery occurs in CFA-inoculated mice but not in AChR plus CFA-inoculated mice. Defective Con A splenic T-cell response seen early after secondary immunization with CFA or AChR in CFA is due to the presence of a defective splenic adherent cell population. Moreover, defective Con A splenic T-cell response seen after established autoimmunity to AChR in EAMG is also due to the presence of a defective splenic adherent cell population.