POTENTIAL THERAPEUTIC RECOMBINANT PROTEINS COMPRISED OF PEPTIDES CONTAINING RECOMBINED T-CELL EPITOPES

The complete primary structure of Fel d I-2 has been determined and sh own to be comprised of two separate polypeptide chains (designated cha in 1 and chain 2), Overlapping peptides covering the entire sequence o f both chains of Fel d I have been used to map the major areas of huma n T cell reactivity. The present study describes three non-contiguous T cell reactive regions of < 30aa in length that were assembled in all six possible configurations using PCR and recombinant DNA methods. Th ese six recombinant proteins comprised of defined non-contiguous T cel l epitope regions artificially combined into single polypeptide chains have been expressed in E. coil, highly purified, and examined for the ir ability to bind to human cat-allergic IgE and for human T cell reac tivity. Several of these recombined T cell epitope-containing polypept ides exhibit markedly reduced IgE binding as compared to the native Fe l d I. Importantly, the human T cell reactivity to individual T cell e pitope-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 epitop e-containing polypeptides inhibits the T cell response to the individu al 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 allerg ic human IgE, constitute a novel potential approach for desensitizatio n to important allergens.