Identification of T cell epitopes derived from cockroach allergens

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Abstract Rationale Sensitization to the German cockroach (Blattella germanica) is a risk factor for asthma. T cell studies to cockroach (CR) could have important implications for therapy by providing insight into T-cell mechanisms governing responses to a “low dose” allergen. Methods The MHC class II prediction algorithm, TEPITOPE, was used to identify peptides within Bla g 1, Bla g 2, Bla g 4 and Bla g 5 containing putative HLA-DR ligands. All of the 16 peptides selected were predicted to bind to at least 4 HLA-DR alleles. Day 6 PBMC proliferation and cytokine responses to purified recombinant CR allergens and peptides were measured in 6 cockroach-sensitive patients (SPT positive +/− CAP ≥0.7IU/ml) and 6 non-sensitized controls. Results Eight peptides stimulated strong PBMC proliferation in controls compared with only 3 peptides in sensitized subjects. No allergen- or peptide-induced proliferation was observed in 3 subjects without IgE ab, 2 of whom had positive skin tests. Peptides from Bla g 1, 2, 4 and 5 induced high levels of IFN-γ (up to 1263pg/ml), IL-6 (up to 2000pg/ml) and IL-10 (up to 342pg/ml), while recombinant Bla g 1 and Bla g 5 induced the highest levels of these cytokines, irrespective of sensitization status. Production of IL-5 and IL-13 was not a major feature of T cell responses to peptides or whole allergen in either patient group. Conclusions Peptides containing putative promiscuous HLA-DR ligands are useful molecular tools for analyzing T cell responses to CR allergens.