Background: Carbohydrates expressed on allergens are known to be important for allergenicity. However, little is known about whether the carbohydrates drive the T(H)2 response.
Objective: We sought to determine a role for carbohydrates expressed on Cry j 1, which is the major allergen of Cryptomeria japonica pollen and causes the most prevalent pollinosis in Japan, in in vitro cellular responses.
Methods: Carbohydrates on Cry j 1 were destroyed by periodate-oxidation under mild conditions. Proliferative responses and cytokine productions against native, periodate-treated, and mock-treated Cry j 1 were compared in peripheral blood mononuclear cells, Cry j 1-specific T-cell lines, and clones from patients with Japanese cedar pollinosis.
Results: We found that peripheral blood mononuclear cells from patients with Japanese cedar pollinosis displayed a significant decrease in proliferation and IL-5 production in response to periodate-treated Cry j 1 in comparison with native and mock-treated Cry j 1. Decreased proliferative responses against periodate-treated Cry j 1 were also seen in polyclonal T-cell lines, and the responses showed a heterogeneity. In addition, Cry j 1-specific CD4+ T-cell clones also displayed a significant decrease in proliferation and IL-4 and IL-5 production-but not IFN-gamma production-in comparison with the control antigens. However, most of the clones showed decreased but positive proliferative responses against periodate-treated Cry j 1. Blockade of the mannose receptor had no effect on cellular responses.
Conclusion: The results suggest that carbohydrates on Cry j 1 play a major role in promoting Cry j 1-specific T(H)2 response in vitro, though they are not major targets as T-cell epitopes.