RESUMO
BACKGROUND: Japanese cedar (Cryptomeria japonica) pollinosis is the most prevalent seasonal rhinitis in Japan. A standardized Japanese cedar pollen extract (CPE) containing 1.5-4.2 µg of Cry j 1 is currently the highest-concentration extract available for allergen-specific immunotherapy (SIT) against this pollinosis. Therefore, we developed a PEGylated fusion protein as a more effective SIT vaccine against Japanese cedar pollinosis. METHODS: The fusion protein of major allergens for Japanese cedar pollen, Cry j 1 and Cry j 2, was expressed in Escherichia coli and conjugated with polyethylene glycol (PEG). The purified PEGylated Cry j 1/2 fusion protein (PEG-fusion) was subcutaneously injected four times into Cry j 1- sensitized mice and CPE-sensitized monkeys. The mice were then subcutaneously challenged with Cry j 1 and serum levels of Cry j 1-specific immunoglobulin, and the proliferation and cytokine production of splenocytes were analyzed. The monkeys were intranasally challenged with CPE and analyzed for Cry j 1-specific immunoglobulin levels in plasma. RESULTS: Cry j 1-specific IgE was significantly attenuated in the PEG-fusion-treated group after Cry j 1-challenge and Cry j 1-specific IgG was significantly increased following PEG-fusion treatment in mice and monkeys. Proliferation and Th2-type cytokine production in splenocytes stimulated with Cry j 1 were also reduced in PEG-fusion-treated mice. IL10 and IL2 production were reduced, but not significantly, while IFN-x03B3; was significantly increased in the PEG-fusion-treated group. CONCLUSIONS: A high-dose injection of PEG-fusion appears to be a valid candidate for a safer and more effective vaccine than the conventional SIT extract for Japanese cedar pollinosis.