CD123 (Cluster of differentiation 123), also known as IL-3R or IL-3RA (Interleukin-3 (IL-3) receptor α-chain), is a membrane receptor belonging to the type I cytokine receptor family. This glycoprotein of 360 amino acids includes a predicted Ig-like domain, a transmembrane domain, an intracellular domain and two FnIII domains and can help transmit the signal of IL-3. The protein encoded by CD123 is an IL-3 specific subunit of a heterodimer composed of α- and β-chains. It is thought to be involved in cell signal transduction for the cell growth and differentiation. CD123 is normally expressed on monocytes, basophils, endothelial cells, and plasmacytoid dendritic cells. It is associated with the development of many diseases and considered as a novel marker in the clinical diagnosis.
Vδ2, a member of the δ-chain family within γδ T-cell receptors (TCRs), exhibits distinct structural and functional attributes critical for immune surveillance. Its variable domain comprises immunoglobulin-like β-sandwich folds stabilized by conserved disulfide bonds, with complementarity-determining regions (CDRs) conferring antigen specificity. CDR3, the most hypervariable loop, directly interacts with non-peptidic antigens like phosphoantigens or lipid metabolites. Functionally, Vδ2⁺ γδ T cells act as innate-like effectors, bridging adaptive and innate immunity by rapidly responding to stress signals and microbial infections. They mediate cytotoxicity via perforin/granzyme pathways and secrete cytokines (e.g., IFN-γ, TNF-α) to modulate immune responses. Notably, Vδ2⁺ cells exhibit MHC-unrestricted antigen recognition, enabling broad reactivity against infected or malignant cells.