Nasal administration of recombinant rat IL-4 ameliorates ongoing experimental autoimmune neuritis and inhibits demyelination

Experimental autoimmune neuritis (EAN) is a CD4(+) T cell-mediated demyelin ating disease of the peripheral nervous system (PNS) and serves as an exper imental model for human immune-demyelinating neurophathies. Ln this study, we examined the effect of recombinant rat interleukin-4 (rrIL-4) on chronic EAN in Lewis rats induced by immunization with PO peptide 180-199 and comp lete Freund's adjuvant (CFA). We estimated that nasal administration of rrI L-4, in dose ranges of 0.1-1 mu g/rat/day in the initial phase of EAN, decr eased the severity and the duration of clinical EAN. Hyporesponsiveness of T cells, downregulation of Th1 cell responses (INF-gamma), but increased le vels of specific IgG1 isotypes document that nasal administration of rrIL-4 was systemically immune effective. Low grade inflammation and complete lac k of regional demyelination within the sciatic nerves were seen in rrIL-4 t reated rats. Based on these observations we suggest that nasal administrati on of IL-4 could be further evaluated, considering its possible use in huma n immune-demyelinating neurophathies. (C) 1999 Academic Press.