Tandem peptide **Cra a T** induces dual immune tolerance to major oyster allergens Cra a 1 and Cra a 2

Oyster allergy, particularly to Crassostrea angulata, is a significant concern, with major allergens identified as tropomyosin (Cra a 1) and arginine kinase (Cra a 2). Current desensitization strategies often target single allergens, leaving a gap for comprehensive treatments addressing multiple allergenic components simultaneously. Developing an effective oral desensitization agent that can induce dual immune tolerance to these co-occurring allergens is crucial for improving patient outcomes and reducing severe allergic reactions. This study explores a novel peptide-based approach to fill this therapeutic void.

Researchers designed a novel tandem peptide, Cra a T, by combining T-cell epitopes from both Cra a 1 and Cra a 2 using bioinformatics and genetic engineering. To evaluate its immunomodulatory potential, they incubated Cra a T with splenocytes harvested from mice previously sensitized to both Cra a 1 and Cra a 2. Additionally, a DC-T coculture system was established to further investigate the peptide's effects on immune cell interactions. The primary endpoints included assessing CD4+T cell proliferation, Treg cell differentiation, interleukin-10 secretion, and the peptide's immunobinding activity against both Cra a 1 and Cra a 2 through serological assays.

The engineered tandem peptide Cra a T demonstrated significant immunomodulatory effects. It consistently stimulated the proliferation of CD4+T cells in splenocytes from sensitized mice, indicating an active immune response. Crucially, Cra a T was found to promote Treg cell differentiation, a key mechanism for inducing immune tolerance, and concurrently upregulated the secretion of interleukin-10, a potent anti-inflammatory cytokine. These findings suggest a shift towards a tolerogenic immune profile. Furthermore, serological assays confirmed that Cra a T exhibited markedly reduced immunobinding activity against both Cra a 1 and Cra a 2 compared to the native allergens. This reduction in binding affinity is critical for a hypoallergenic desensitization agent. The combined results strongly support the peptide's potential to induce dual immune tolerance.

Cra a T consistently stimulated CD4+T cell proliferation, promoted Treg cell differentiation, and upregulated interleukin-10 secretion, while also showing markedly reduced immunobinding to both Cra a 1 and Cra a 2.