Peripheral nervous system (PNS) expression of mRNAs encoding myelin proteins and Fc γ RIII during experimental allergic neuritis

Experimental allergic neuritis (EAN) was induced in Lewis rats by injection of 'SP26', a peptide homologous to amino acids 53-78 of bovine myelin P2 protein, in complete Freund's adjuvant. The rats developed signs of EAN which began on day 14, were maximal on day 18, and had subsided by day 30. RNA content of cauda equina and sciatic nerves increased more than 2-fold at the height of EAN. Expression of myelin Po and PI mRNAs did not fall during EAN, nor rise during recovery. Fc γ mRNA, which encodes Fc γ RIII, an immunogloubulin-binding protein mediating activation of natural killer cells and macrophages by immune complexes, was transiently, but markedly induced in scattered endoneural cells, presumably macrophages, in cauda equina and sciatic nerves during the period of increasing weakness.