Recognition of T cell epitopes unique to Cha o 2, the major allergen in Japanese cypress pollen, in allergic patients cross-reactive to Japanese cedar and Japanese cypress pollen.

BACKGROUND Pollens from species of the Cupressaceae family are one of the most important causes of respiratory allergies worldwide. Many patients with pollinosis have specific IgE to both allergens from Japanese cedar and Japanese cypress pollen. We set out to identify T cell epitopes in Cha o 2, the second major allergen of Japanese cypress pollen. METHODS T cell lines (TCL) and T cell clones (TCC) specific to Cha o 2 were generated from allergic patients cross-reactive to Japanese cedar and Japanese cypress pollen. T cell epitopes in Cha o 2 were identified by responses of TCL stimulated with overlapping peptides. Abilities of IL-4/IFN-gamma production by TCC were evaluated using enzyme immunoassay. RESULTS Using TCL, 11 dominant and subdominant T cell epitopes were identified in Cha o 2. The subsets of TCC were predominantly of T helper 2-type. A T cell epitope p141-160 in Cha o 2 and corresponding peptide in Cry j 2 showed high homology. Although TCC PC.205.159 responded to stimulation with p141-160 in Cha o 2, it did not respond with corresponding peptide in Cry j 2, therefore, the T cell epitope was unique to Cha o 2. CONCLUSIONS Eleven T cell epitopes that were identified are unique to Cha o 2. Cha o 2 is a putative aeroallergen that can potentially sensitize human T cells. We concluded that generation of T cells specific to Cha o 2 in allergic patients acts as one of the causes of continuous allergic symptoms in April.