title: Survival of memory T cells specific for Japanese cypress pollen allergen is maintained by cross-stimulation of putative pectate lyases from other plants.
abstract: In view of recent studies on the mechanisms of the survival of peripheral memory T cells, we tested the biologic role of pectate lyase, a pectin-degrading enzyme, as the cross-reactive antigen required for the recurring survival signals for human T cells specific for Cha o 1, a pollen allergen molecule of the Japanese cypress. We determined a 16-mer epitope peptide for the T-cell clone, and prepared synthetic oligopeptides of homologous regions in putative pectate lyase of other plants. Of these homologous peptides, ZePel (Zinnia elegans), ban 17 (banana), and Amb a 1.1 (short ragweed) induced strong proliferative responses of the Cha o 1-specific T-cell clone in vitro. In addition, suboptimal doses of peptide homologs derived from banana and short ragweed enhanced the survival potency of this T-cell clone without detectable proliferative responses to the peptides. When there was no antigen stimulation, the T-cell clone decreased in viable cell number and lost antigen-specific proliferation activity on day 6 during in vitro incubation. On the other hand, T-cell clones incubated with these survival-inducing peptides maintained proliferative activity to Cha o 1 even on day 9. Serum derived from the donor patient did not contain detectable levels of IgE specific to banana or short ragweed by CAP-RAST. These results show that human T cells specific for pollen allergen seem to use cross-reactive pectate lyase peptides to deliver survival signals even in the absence of pollen allergen, and memory T cells maintained in such a manner might be functioning at the onset of allergic pollinosis, although pollen allergens are seasonal.
authors.affiliation: Department of Otorhinolaryngology, Nagoya City University Medical School, Nagoya, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: S
authors.initials: S
authors.lastname: Takagi
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Ito
authors.forename: S
authors.initials: S
authors.lastname: Murakami
authors.forename: N
authors.initials: N
authors.lastname: Ohta
mesh_terms: D000485:Allergens; D052179:Antigens, Plant; D003429:Cross Reactions / Q000276:immunology; D005638:Fruit / Q000201:enzymology; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000097:blood* / Q000276:immunology; D007156:Immunologic Memory / Q000276:immunology*; D019668:Liliaceae / Q000201:enzymology; D018551:Solanum lycopersicum / Q000201:enzymology; D000455:Medicago sativa / Q000201:enzymology; D018532:Pisum sativum / Q000201:enzymology; D010940:Plant Proteins / Q000009:adverse effects* / Q000235:genetics / Q000276:immunology*; D011058:Pollen / Q000276:immunology*; D011133:Polysaccharide-Lyases / Q000235:genetics / Q000276:immunology*; D011852:Radioallergosorbent Test; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014197:Trees; D019862:Zingiberales / Q000201:enzymology
chemical_list: D000485:Allergens; C038640:Amb a VI protein, Ambrosia artemisiifolia; D052179:Antigens, Plant; C408445:Cha o 1 protein, Chamaecyparis obtusa; D010940:Plant Proteins; D007073:Immunoglobulin E; D011133:Polysaccharide-Lyases; C023911:pectate lyase