Pattern-recognition and other uptake receptors on antigen-presenting cells engaged by keyhole limpet hemocyanin (PRRs/CLRs)

Pattern-recognition and other uptake receptors on antigen-presenting cells (APCs) engaged by keyhole limpet hemocyanin (KLH) are a specialized group of surface molecules, primarily C-type lectin receptors (CLRs) such as the mannose receptor (CD206) and DC-SIGN (CD209), that mediate the recognition and internalization of KLH (Presotto et al., 2008). KLH is a large, highly glycosylated protein from the marine mollusk Megathura crenulata, and its complex carbohydrate moieties (e.g., mannose, fucose, and Gal(beta 1-3)GalNAc) serve as ligands for these receptors (Wirquin et al., 1995). Upon binding, these receptors facilitate receptor-mediated endocytosis, allowing for the efficient processing and presentation of KLH-derived peptides or conjugated haptens to T cells. Furthermore, the engagement of these receptors triggers intracellular signaling cascades, including the Syk and NF-kappaB pathways, which induce the maturation of dendritic cells and the secretion of pro-inflammatory cytokines like IL-12 (Presotto et al., 2008). This activation promotes a Th1-skewed immune response, which is the basis for KLH's use as a potent vaccine adjuvant and as an immunotherapeutic agent for superficial bladder cancer. Understanding the interaction between KLH and these receptors is crucial for optimizing immunotherapies and monitoring patient immune status through biomarkers such as DC maturation markers and cytokine profiles.

Other names

C-type lectin receptorsMannose receptorCD206DC-SIGNCD209Pattern recognition receptors on APCsUptake receptors on antigen-presenting cells

Binding of the highly glycosylated KLH molecule to pattern-recognition receptors (primarily C-type lectins like the mannose receptor and DC-SIGN) on antigen-presenting cells triggers receptor-mediated endocytosis and activates intracellular signaling pathways such as Syk and NF-kappaB. This process induces the maturation of dendritic cells, characterized by the upregulation of costimulatory molecules and the secretion of pro-inflammatory cytokines like IL-12, ultimately promoting a potent T-cell-dependent immune response.