Phleum pratense-specific T cells of allergic rhinitis patients display a broader recognition pattern than Phleum pratense-specific serum immunoglobulin E

Background The role of allergen-specific CD4(+) T lymphocytes in the pathop hysiology of atopic disease is well established. Previous studies on allerg en-specific T-cell responses have focused on the recognition of single majo r allergens to identify T-cell epitopes. Objective However, it is not clear whether immune responses to allergen ext racts are exclusively targeted at major allergens or whether additional pro teins are recognized. Methods Here we describe the Phleum pratense-specific immunoglobulin E (IgE ) and T-cell responses of six allergic rhinitis patients. Reactivity was me asured to size-separated fractions of a P. pratense extract as well as to t he purified major allergens Phl p 1, Phl p 2/3 and Phl p 5. Results The specificity of the patients' serum IgE, measured in a fluid pha se assay, was restricted to one or two of the major allergens. Even though the majority of the patients had IgE antibodies reactive with a single majo r allergen, one patient reacted with both Phl p 5 and with Phl p 2/3. Analy sis of the T-cell repertoire with P. pratense-specific T-cell lines (TCLs) and CD4(+) T-cell clones (TCCs) revealed that at least six different protei ns were recognized, including the three major allergens, most notably Phl p 5. Simultaneous production of IL-5 and interferon (IFN) -gamma was detecte d in supernatants of the TCLs stimulated with P. pratense extract and the m ajor allergens. Conclusion These results indicate that allergic rhinitis patients have a la rge pool of circulating allergen-specific CD4(+) T cells that recognize man y different proteins in an allergenic extract, whereas only a small number of these proteins are recognized by serum IgE.