Characterization of infiltrating mononuclear cells in the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis (EAE)

: Mononuclear cells (MNCs) infiltrating in spinal cords (SCs) of Lewis rats with EAE were isolated in order to permit flow cytometric (FCM) analysis of these cell populations, using monoclonal antibody to T cell, CD4, CD8. MHC class II antigen (Ia), intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function associated antigen-1 (LFA-1). The number of MNCs isolated from SC varied from 5 to 620 x 10(4). They were increased and reached a peak on day 2 post clinical onset, and subsequently declined through the clinical course. The increase of infiltrating cells in SC paralleled the severity of the disease development. The surface phenotypes of MNCs from rats on the day of clinical onset were determined by flow cytometry. The phenotypes found in these rats were as follows: T cells (70.3%); CD4 + (58.3%); CD8 + (40.3%); Ia (51.9%); ICAM-1 (62.6%); LFA-1 (75.8%). These findings suggest that high proportion of ICMA-1 and LFA-1 expression may be important in antigen presentation in the inflammatory lesions of SC and in promoting lymphocyte extravasation across the blood-brain barrier during the disease. The approach we employed offered more sophisticated and quantitative analysis of CNS inflammatory cells, which is unobtainable by tissue section staining.