Tumor-associated antigens and NKG2D ligands (TAA/NKG2DL)

Tumor-associated antigens (TAAs) and NKG2D ligands (NKG2DLs) constitute the primary molecular targets recognized by Cytokine-Induced Killer (CIK) cells, particularly when enhanced by Dendritic Cell (DC) activation [1, 2]. TAAs are typically intracellular proteins that are overexpressed or mutated in cancer cells and presented as peptide fragments on the cell surface by Major Histocompatibility Complex (MHC) molecules [6, 18]. These complexes are recognized by the T-cell receptors (TCRs) present on the CD3+ subset of CIK cells, facilitating an adaptive immune response [1, 13]. Concurrently, NKG2DLs—such as MHC class I polypeptide-related sequence A/B (MICA/B) and UL16-binding proteins (ULBPs)—are stress-induced surface proteins that are upregulated in malignant tissues [2, 9]. These ligands are recognized by the NKG2D receptor on CIK cells in an MHC-unrestricted manner, providing a potent innate-like cytotoxic mechanism that is effective even against tumor cells that have downregulated MHC expression to evade T-cell detection [1, 16]. The synergy between TCR-mediated and NKG2D-mediated recognition allows DC-CIK therapy to target a broad range of hematological and solid tumors [7, 12]. Therapeutic interventions primarily involve the adoptive transfer of autologous or allogeneic CIK cells expanded ex vivo with cytokines like IL-2 and IFN-gamma, often combined with dendritic cells to prime the cells against specific tumor lysates or peptides [4, 11]. This dual-targeting approach addresses the limitations of therapies that rely solely on MHC-restricted recognition, offering a versatile tool for cancer immunotherapy [1, 10].

Other names

Tumor-associated antigensNKG2D ligandsMICA/BULBPsMHC-peptide complexesCIK cell targetsStress-induced ligands

Adoptive cell transfer involving dual recognition of tumor cells via T-cell receptors (TCR) and NKG2D receptors, leading to perforin- and granzyme-mediated cytolysis.