Polarization toward the T-helper(Th)1 type immune response is not required for rat experimental autoimmune myasthenia gravis

Recall immune memory: a new tool for generating late onset autoimmune myasthenia gravis

Most patients with autoimmune myasthenia gravis (MG) produce autoantibodies against their muscle acetylcholine receptors (AChR), causing debilitating muscle weakness. Approximately 60% of MG patients first exhibit myasthenic symptoms after the age of 40. Yet, in the C57BL/6 mouse model of MG, older mice are resistant to induction of myasthenia gravis. To understand the immunological basis for this resistance, the effects of age on the B-cell responses to AChR from Torpedo californica, the inducing antigen, were addressed. As expected, the primary B-cell response was lower in 20-month-old mice than in 2-month-old mice; the isotype profile was not altered by age. When mice were re-immunized, the anti-T-AChR titers increased in both young and old animals, suggesting that a memory response was elicited. Importantly, memory B-cells activated in young animals were largely resistant to the age-associated loss of immune function and the recall memory response was vigorous. Furthermore, the antibodies produced in re-stimulated older mice were functional, as evidenced by the appearance of MG symptoms in some of these animals. Thus, by eliciting a recall memory response, the first examples of late onset MG in mice have been generated. By analogy, late onset MG in humans may be due to re-activation of B-cell responses initiated at a younger age.

The Wistar Kyoto (RT1(l)) rat is resistant to myelin basic protein-induced experimental autoimmune encephalomyelitis: comparison with the susceptible Lewis (RT1(l)) strain with regard to the MBP-directed CD4+ T cell repertoire and its regulation

Here, we demonstrate that the Wistar Kyoto (WKY/NHsd) rat, which bears the same RT1(l) haplotype as the experimental autoimmune encephalomyelitis (EAE)-susceptible Lewis rat strain, is highly resistant to myelin basic protein (MBP)-induced EAE. No differences between Lewis and WKY strains were found in T cell proliferative specificity or the use of Vbeta8.2 T cell receptors in response to MBP. A Th2 cytokine bias correlated with WKY's EAE resistance. MBP challenge of WKY-into-Lewis adoptive transfer recipients produced a novel biepisodic EAE. The WKY strain should be useful in studies of many tissue-specific autoimmune diseases to which the Lewis rat is susceptible.