Expression of accessory molecules for T-cell activation in peripheral nerve of patients with CIDP and vasculitic neuropathy

Vasculitic neuropathy and chronic inflammatory demyelinating polyneuropathy (CIDP) are neuropathies characterized by a T-lymphocyte infiltrate in the peripheral nerves. The microenvironment in which these T cells become activ ated, and the molecules and cells that play a role in this process are inco mpletely understood. Using immunohistochemical analysis, we studied the eff ect of the presence of adhesion, costimulatory and antigen-presenting molec ules on different cell types as a precondition for local T-cell activation in human sural nerve biopsies of seven patients with CIDP, three patients w ith vasculitic neuropathy and three healthy controls. In biopsies from CIDP and vasculitic neuropathy patients, but not in those from healthy controls , Schwann cells expressed the adhesion/T-cell stimulatory molecule CD58 (LF A-3). The CD58 molecule was also present on endothelial cells of all vascul itic neuropathy patients and one CIDP patient. In biopsies from normal cont rols and patients, CD54 (ICAM-1) expression was detectable on microvascular endothelial cells. In addition, expression of the costimulatory molecule C D86 was detected on vascular tissue in patients with vasculitic neuropathy. Although macrophages were always present in all subjects, expression of th e major histocompatibility complex (MHC)-like molecule CD1a by macrophages was restricted to biopsies from two CIDP patients and one vasculitic neurop athy patient. Unexpectedly, Schwann cells of a single vasculitis patient st rongly expressed CD1b, a molecule involved in the presentation of self-glyc olipids to T cells. Schwann cells in biopsies from patients and normal cont rols expressed high levels of the invariant chain, CD74, a molecule involve d in the intracellular sorting of MHC class II molecules, There was no evid ence for the presence of dendritic cells in sural nerve biopsies. These fin dings support a model in which T-cell activation can be initiated and/or pe rpetuated locally in sural nerve biopsies of patients with CIDP and vasculi tic neuropathy, and predict an important role for Schwann cells and endothe lial cells.