Flow cytometric analysis of infiltrating cells in the peripheral nerves in experimental allergic neuritis

Experimental autoimmune neuritis (EAN) is an animal model that shares clinical, pathological and electrophysiological features with the human disease Guillain-Barre syndrome (GBS). In this study, we isolated and characterized by fluorescent activated cell sorter (FACS) phenotype of the inflammatory cells infiltrating cauda equina (CE) of Lewis rats at the active stage of the disease. We found that at this stage of EAN macrophages (M phi) and alpha beta T cells were two major populations isolated from CE. We also found that among total cell population isolated from CE, gamma delta T and NK cells composed two small but distinct populations, while B cells were negligible. We characterized phenotype of alpha beta T cells in CE as CD45RC(+)CD8(+) (activated cytotoxic lymphocytes) and CD45RC(-)CD4(+) (memory Th cells). The phenotype of gamma delta T cells was found to be consisted of only CD45RC(+)CD8(+) cells. Both alpha beta and gamma delta T cells in CE expressed a higher level of CD25, CD44 and CD54 activation markers compared to the other tissues. Immunohistochemistry demonstrated that gamma delta T cells existed apart from the intense cellular infiltrate. This is the first report on the isolation and FAGS analysis of CE-infiltrating cells, contributing a new and alternative approach to study the inflammatory lesions in EAN. We conclude that both alpha beta and gamma delta T cells have a unique activation/inflammatory phenotype required to traffic through and be retained in the peripheral nerves during EAN. (C) 2000 Elsevier Science BN. All rights reserved.