Immunocytochemical identification and quantitation of mononuclear cells in the meninges during the development of chronic relapsing experimental allergic encephalomyelitis (CREAE) in the guinea pig.

To investigate the role of mononuclear cells in the meninges at all stages of chronic relapsing experimental allergic encephalomyelitis, juvenile guinea pigs were inoculated with isogeneic spinal cord in Freund's complete adjuvant (FCA) in parallel with animals inoculated with FCA alone as age-matched controls. Cytospins were prepared of the meningeal inflammatory cells obtained by washing the brains of these animals. These cytospins were stained by indirect immunoperoxidase, using a panel of monoclonal antibodies (Mabs) recognizing "activated" macrophages (M phi s), Ia antigen, total T cells and a putatively T-cell-suppressor subset, and an antiserum against immunoglobulins. The inflammatory response was quantitated and the proportions of the different cell types were determined. It was found that the total number of infiltrating cells correlated with the neurological symptoms of the disease. "Activated" M phi s increased significantly during the disease, in line with clinical signs. The expression of the Ia antigen, found on both lymphocytes and M phi s, also appeared to correlate with the disease. There was no increase in putative T-suppressor-cells during remission but there was a significant rise in the proportion of both cells staining with anti-immunoglobulins and plasma cells during relapse.