Electrophysiological follow up of experimental allergic neuritis mediated by a permanent T cell line in rats

Acute experimental allergic neuritis (EAN) was produced in Lewis rats by transfer of lymphocytes from a permanent T cell line specific for bovine P2 protein. In 3 groups of rats receiving 10(4), 10(5) and 10(6) total injected P2-specific lymphocytes, respectively, the time course of illness was followed by measuring several electrophysiological parameters including the H reflex or F wave and lumbospinal somatosensory evoked potentials (SEP). The severity and time course of both the electrophysiological and clinical (e.g., loss of weight and development of paresis) parameters of illness depended on the number of injected lymphocytes. Lower numbers of injected cells were correlated with a later onset and less severe symptoms as well as with an earlier and more complete recovery. According to clinical observation EAN mediated by lymphocytes is a monophasic illness. According to our electrophysiological measurements, however, the disease can be described by the following successive stages: (a) an early stage of hyperexcitability; (b) a stage of acute partial conduction block; (c) 14 days later a stage of maximal demyelination; and (d) a recovery phase. Although demyelination is the prominent feature of the disease, axonal degeneration also occurs to an extent directly related to the number of cells injected. Degeneration was not observed in rats from the group with the lowest number (10(4] of injected lymphocytes.