Major cat allergen Fel d 1-specific CD4+ T cell receptor (Fel d 1-specific TCR)

The "Major cat allergen Fel d 1-specific CD4+ T cell receptor" refers to the antigen-recognizing component expressed on helper-type CD4+ T lymphocytes that specifically bind peptides derived from *Fel d 1*, the principal protein responsible for most human cat allergies. These receptors are part of the adaptive immune system’s mechanism for recognizing foreign antigens presented by MHC class II molecules. Upon encountering *Fel d 1* peptides presented by antigen-presenting cells, these specialized receptors trigger activation signals leading to clonal expansion and differentiation into various effector subsets such as Th2-like cells producing IL‑4, IL‑5, IL‑13 cytokines that promote IgE production—a hallmark in allergy pathogenesis. Other subsets like Th9 and Th17 may also be involved in modulating inflammatory responses. The balance between pathogenic effector phenotypes and regulatory populations expressing markers like FoxP3 influences clinical outcomes ranging from mild rhinitis to severe asthma or anaphylaxis. Therapeutic strategies aim at modifying these interactions either through desensitization protocols using modified allergens displayed on virus-like particles or other immunomodulatory approaches. This target is not a single molecular entity but rather denotes a functional specificity within the diverse repertoire of human αβ-T cell receptors expressed on helper memory/effector lymphocytes responding specifically against *Fel d 1*. Understanding its role provides insight into mechanisms underlying common mammalian-origin allergies affecting approximately one-fifth of adults worldwide. This summary integrates molecular classification as an adaptive immune receptor complex with biological roles centered around allergy pathogenesis mediated through *Fel d* *¹*-specific recognition by CD4-positive helper T-cells.

Other names

Fel d 1-reactive CD4+ T-cell receptorAllergen-specific CD4+ TCR for Fel d 1

Induction of immune tolerance by altering activation or expansion of Fel d1-specific CD4+ T cells (e.g., virus-like particle-based vaccines displaying Fel d1); Modulation of cytokine profiles from pathogenic Th2/Th9/Th17 subsets toward regulatory phenotypes