Ia-expressing cells and T lymphocytes of different subsets in peripheral nerve tissue during experimental allergic neuritis in Lewis rats.

Inflammatory infiltrates in sciatic nerves during the acute phase of experimental allergic neuritis in the Lewis rat have been characterized with regard to occurrence and distribution of Ia-expressing cells and T-lymphocyte subsets by the help of an immunohistochemical double-staining technique, enabling the simultaneous visualization of T lymphocytes and Ia-expressing non-T cells. Large numbers of Ia-expressing irregular macrophage-like/dendritic cells were seen both within inflammatory infiltrates and within afflicted nervous tissue. Many W3/13-reactive T lymphocytes of both 'helper' and 'suppressor/cytoxic' phenotypes appeared in close contact with these Ia-expressing non-T cells, particularly within the infiltrates. B lymphocytes and plasma cells were relatively few and mainly found close to endoneurial vessels.