Monomeric DR2/MOG-35-55 recombinant TCR ligand treats relapses of experimental encephalomyelitis in DR2 transgenic mice.

Treatment of human autoimmune diseases such as multiple sclerosis (MS) will likely require agents that can prevent or reverse the inflammatory process that results in clinical relapses and disease progression. We evaluated the ability of a newly designed monomeric recombinant TCR ligand (RTL342M) containing HLA-DR2 peptide-binding domains covalently linked to MOG-35-55 peptide to prevent and treat both the initial episode and subsequent relapses of experimental autoimmune encephalomyelitis (EAE) in HLA-DR2 transgenic mice. Single doses of RTL342M given either i.v. or s.c. to HLA-DR2 mice produced a rapid (within 24 h) and dose-dependent reversal of clinical signs of paralytic EAE, and even a single dose < or = 2 microg could produce a significant treatment effect. Multiple daily doses were even more effective than the same total amount of RTL given as a single dose. By establishing the minimal effective dose, we determined that RTLs may be 50 times more potent than molar equivalent doses of myelin peptide alone. RTL342M given prior to induction of EAE prevented disease in most mice, and the remainder could be successfully retreated with RTL. Most important for clinical application, RTL342M was highly effective for treating EAE relapses when given periodically prior to the relapse or even after relapses had occurred. These data demonstrate the rapid and potent clinical effects of RTL342M at disease onset and during relapses in EAE and establish important principles governing the application of this novel approach as a possible therapy for patients with MS.

AlphaB-crystallin-reactive T cells from knockout mice are not encephalitogenic.

Alpha B-crystallin (alphaB) is a small heat shock protein that is strongly up-regulated in multiple sclerosis (MS) brain tissue, and can induce strong T cell responses. Assessing a potential encephalitogenic function for alphaB protein in MS and experimental autoimmune encephalomyelitis (EAE) has been challenging due to its ubiquitous expression that likely maintains central and peripheral tolerance to this protein in mice. To address this issue, we obtained alphaB-knockout (alphaB-KO) mice in H-2b background that lack immune tolerance to alphaB protein, and thus are capable of developing alphaB-specific T cells that could be tested for encephalitogenic activity after transfer into alphaB-expressing wild type (WT) mice. We found that T cell lines from spleens of alphaB protein-immunized alphaB-KO mice proliferated strongly to alphaB protein itself, and the majority of T cells were CD4+ and capable of secreting pro-inflammatory Th1 cytokines upon restimulation. However, transfer of such alphaB-reactive T cells back into WT recipients was not sufficient to induce EAE, compared to the transfer of mouse MOG-35-55 peptide-reactive T cells from the same donors that induced severe EAE in recipients. Moreover, alphaB-specific T cells failed to augment severity of actively induced EAE in WT mice that were expressing high levels of alphaB message in the CNS at the time of transfer. These results suggest that alphaB-specific T cells are immunocompetent but not encephalitogenic in 129SvEv mice, and that immune tolerance may not be the main factor that limits the encephalitogenic potential of alphaB.