Characterization of the immunopathogenic responses to ovalbumin peptide 323-339 in experimental immune-mediated blepharoconjunctivitis in Lewis rats.

PURPOSE

We recently reported the essential role of cellular immunity on the induction of experimental immune-mediated blepharoconjunctivitis (EC, formerly EAC) by using ovalbumin (OVA) as a model antigen in Lewis rats. The purpose of this study was to investigate the possible induction of EC by immunization with an OVA peptide (OVA 323-339).

METHODS

Lewis rats were immunized with various doses of OVA or OVA 323-339 in complete Freund's adjuvant. Three weeks later they were challenged with OVA or OVA 323-339 by eye drops; 24 h after challenge, eyes including lids, lymph nodes and blood were harvested after clinical evaluation. An OVA 323-339-specific cell line (S816) was established by periodical stimulation with this peptide. Pathogenicity of S816 was tested by adoptive transfer of S816 into syngeneic recipient rats after challenge with OVA or OVA 323-339.

RESULTS

All rats immunized with OVA 323-339 developed EC after challenge with OVA or OVA 323-339. Rats immunized with OVA 323-339 at doses as low as 0.01 microg had severe clinical scores. OVA-primed rats also developed EC after challenge with OVA 323-339. OVA-primed lymph node cells responded to OVA but not to OVA 323-339. OVA 323-339-primed lymph node cells responded to OVA 323-339 but not to OVA and produced IFN-gamma by stimulation with either OVA or OVA 323-339 (three- to fourfold more than with OVA-primed lymph node cells). Recipient rats of S816 developed severe EC after challenge with either OVA or OVA 323-339.

CONCLUSION

OVA 323-339 was identified as a potent pathogenic peptide in EC.