In vivo treatment of rats with monoclonal antibodies against gamma interferon: effects on experimental allergic neuritis.

To elucidate the role of gamma interferon in experimental allergic neuritis (EAN) a mouse monoclonal antibody (DB-1) directed against rat gamma interferon was used to treat rats during different phases of the development of experimental allergic neuritis (EAN). The effects of this treatment were followed by clinical evaluation, and in some instances by immunohistochemical analysis of lymphoid organs and affected nerves for presence of MHC class II antigens and various T cell subsets. DB-1 treatment given after onset of clinical symptoms (Day 15 after immuniozation with myelin) shortened disease duration, compared with non-treated EAN controls. Affected nerves of DB-1 treated animals showed reduced expression of MHC class II antigens and lower numbers of T lymphocytes within the affected nerves. In contrast, when DB-1 treatment was given on the day of immunization (Day 0), the disease duration increased, and when given before onset of the disease (Day 9) the clinical course was not significantly affected. The results support an important role for gamma interferon in the pathogenesis of EAN.