Melatonin (N-acetyl-5-methoxytryptamine), a pineal neurohormone, is a hydroxyl radical scavenger and antioxidant, and plays an important role in the immune system. We studied the effect of exogenous melatonin on the pathogenesis of experimental autoimmune encephalomyelitis (EAE). EAE was induced in Lewis rats by immunization with rat spinal cord homogenates. Subsequent oral administration of melatonin at 5 mg/kg significantly reduced the clinical severity of EAE paralysis compared with administration of the vehicle alone (p<0.01). Infiltration of ED1 macrophages and CD4 T cells into spinal cords occurred both in the absence and presence of melatonin treatment, but melatonin-treated rats had less spinal cord infiltration of inflammatory cells than did the control group. ICAM-1 immunoreactivity in the blood vessels of EAE lesions was decreased in melatonin-treated rats compared to vehicle-treated rats. These findings suggest that exogenous melatonin ameliorates EAE via a mechanism involving reduced expression of ICAM-1 and lymphocyte function associated antigen-1a in autoimmune target organs.
Animals ; Encephalomyelitis, Autoimmune, Experimental/*immunology/prevention & control ; Female ; Immunohistochemistry ; Intercellular Adhesion Molecule-1/analysis/*immunology ; Male ; Melatonin/administration & dosage/*physiology ; Rats ; Rats, Inbred Lew ; Spinal Cord/chemistry/pathology

Intradermal gene administration was found to induce a more profound immune response than direct intramusclular gene injection. We performed intradermal vaccination of B10.PL mice with DNA encoding for the V 8.2 region of the T-cell receptors (TCR). Three weeks later, these mice were immunized with rat myelin basic protein (MBP). Daily mean clinical scores and mortality rate were lower in this group compared with controls. The proliferative responses of lymph node cells to rat MBP were slightly less in the vaccination groups than in the control groups (p<0.05). However, we detected no differences between the two groups with regard to the production of MBP-specific IgG, IgG1, & IgG2a antibodies. The levels of cytokine mRNA expression in the vaccination groups were observed higher than in the control groups without antigen-specific stimulation, but all of cytokine expressions between the vaccination and control groups after antigen-specific stimulation were identical. These results demonstrate that intradermal DNA vaccines encoding for TCR might prove to be useful in the control of autoimmune disease.
Animals ; Autoantibodies/blood ; Base Sequence ; Cytokines/genetics ; DNA, Complementary/genetics ; Encephalomyelitis, Autoimmune, Experimental/etiology/immunology/*prevention and control ; Female ; Gene Expression ; *Genes, T-Cell Receptor beta ; In Vitro ; Injections, Intradermal ; Lymphocyte Activation ; Mice ; Myelin Basic Proteins/immunology ; RNA, Messenger/genetics/metabolism ; Rats ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Vaccines, DNA/*administration and dosage/genetics