CTLA-4 recombinant protein genetically fused to canine Fcepsilon receptor Ialpha enhances allergen specific lymphocyte responses in experimentally sensitized dogs

Vaccination with a recombinant antigen fused to a targeting molecule is a potential strategy for inducing efficient immune responses. For the therapeutic purpose of allergic diseases in dogs, a DNA construct which expresses recombinant fusion protein with two functional domains, cytotoxic T lymphocyte antigen (CTLA-4) and Fcepsilon receptor Ialpha, was developed to bridge antigen-presenting cells and IgE-allergen complex. The recombinant fusion protein expressed by the DNA construct was demonstrated to retain the ability to bind monocytes in PBMC and dog IgE, respectively. Additionally, the recombinant protein induced enhancement of allergen-induced lymphoproliferation in experimentally sensitized dogs under conditions of suboptimal allergen stimulation. These results indicated that the DNA construct could enhance allergen-induced immune responses in vivo, implying its usefulness for perspective application in immunotherapy in dogs.