Bruce L. Rogers

Potential therapeutic recombinant proteins comprised of peptides containing recombined T cell epitopes

The complete primary structure of Fel d I2 has been determined and shown to be comprised of two separate polypeptide chains (designated chain 1 and 2). Overlapping peptides covering the entire sequence of both chains of Fel d I have been used to map the major areas of human T cell reactivity. The present study describes three non-contiguous T cell reactive regions of < 30 aa in length that were assembled in all six possible configurations using PCR and recombinant DNA methods. These six recombinant proteins comprised of defined non-contiguous T cell epitope regions artificially combined into single polypeptide chains have been expressed in E. coli, highly purified, and examined for their ability to bind to human cat-allergic IgE and for human T cell reactivity. Several of these recombined T cell epitope-containing polypeptides exhibit markedly reduced IgE binding as compared to the native Fel d I. Importantly, the human T cell reactivity to individual T cell epitope-containing regions is maintained even though each was placed in an unnatural position as compared to the native molecule. In addition, T cell responses to potential junctional epitopes were not detected. It was also demonstrated in mice that s.c. injection of T cell epitope-containing polypeptides inhibits the T cell response to the individual peptides upon subsequent challenge in vitro. Thus, these recombined T cell epitope-containing polypeptides, which harbor multiple T cell reactive regions but have significantly reduced reactivity with allergic human IgE, constitute a novel potential approach for desensitization to important allergens.

Immunological Characterization of the Major Ragweed Allergens Amb a I and Amb a II

Pollen from short ragweed (Ambrosia artemisiifolia) is the source of one of North America’s most important allergens (King, 1976). Ambrosia artemisiifolia is a widespread weed of the Compositae family, which is comprised of several related species (King and Norman, 1986). Although the pollinating season for ragweed varies depending on the geographical location, it is generally from midsummer to late autumn in the eastern and central United States. Approximately 10% of the U.S. population is allergic to ragweed pollen, making this allergen source highly significant in terms of clinical disease.