Analysis of human T cell clones reactive with group V grass pollen allergens.

Twenty-seven T cell clones (TCC) reactive with group V allergens of Phleum pratense (Phlp V) were established from the peripheral blood of 3 patients allergic to grass pollen. Twenty-four TCC showed the helper cell phenotype CD3+, CD4+, CD8-; the remaining clones were CD3+CD4-CD8+. T cell recognition of Phlp V was exclusively HLA-DR restricted. Many of the Phlp V reactive TCC (19 of 27; 70%) were stimulated additionally by other group V allergens isolated from Lolium perenne, Poa pratensis, and Dactylis glomerata. These data indicate the existence of cross-reacting T cell epitopes among group V allergens of different grasses. The Phlp V triggered cytokine production demonstrated in 13 out of 24 CD4+ TCC a Th2-like pattern (high interleukin 4/gamma-interferon ratios) suggesting group V allergens as important targets of grass pollen specific IgE.