IDENTIFICATION OF T-CELL EPITOPES OF LOL-P-9, A MAJOR ALLERGEN OF RYEGRASS (LOLIUM-PERENNE) POLLEN

T-cell recognition of Lol p 9, a major allergen of ryegrass pollen, wa s investigated by using a T-cell line and T-cell clones generated from the peripheral blood of an atopic donor. The T-cell line reacted with purified Lol p 9, as well as with crude ryegrass pollen extract, but failed to cross-react with Bermuda grass pollen extract. All of six T- cell clones generated from this line proliferated in response to Lol p 9. Epitope mapping was carried our with a panel of 34 overlapping syn thetic peptides, which spanned the entire sequence of the Lol p 9 12R isoform. The T-cell line responded to two of the peptides, Lol p 9 (10 5-116) and Lol p 9 (193-204), whereas reactivity with one oi other of these peptides was shown by five T-cell clones. These two peptides con tained sequences consistent with motifs previously reported for major histocompatibility complex class II-restricted peptides. HLA antibody blocking studies showed that presentation of peptide Lol p 9 (105-116) to one T-cell clone was HLA-DR-restricted; this clone expressed a T h elper cell phenotype (CD3(+), CD4(+)) and the T-cell receptor alpha be ta. The identification of immunodominant T-cell epitope(s) on allergen s is essential for, devising safer and more effective immunotherapy st rategies, which can interrupt the chain of events leading to allergic disease.