CD Molecules Nomenclature 2025: Antibody Validation and Expression Profiling of Immune System G Protein-Coupled Receptors

Monoclonal antibodies (mAbs) targeting cell-surface molecules are pivotal in biomedical research, diagnostic applications, and biotechnology. Over the past four decades, the CD nomenclature system, established by the Human Leukocyte Differentiation Antigens Workshops and endorsed by the International Union of Immunological Societies (IUIS), has provided a standardized naming convention for both mAbs and the cell surface molecules they target. G protein-coupled receptors (GPCRs) represent the largest family of cell-surface receptors, playing essential roles in both innate and adaptive immune responses. Despite their significance, GPCRs are underrepresented in terms of well-validated mAbs available for flow cytometry and therapeutic applications. At the Eleventh HLDA Workshop (HLDA11), new CD nomenclature has been assigned to thirteen GPCR cell-surface molecules expressed on immune cells: CD198 (CCR8), CD199 (CCR9), CD372 (CCR10), CD373 (CX3CR1), CD374 (XCR1), CD375 (GPR15), CDw376 (GPR26), CD377 (SSTR3), CD378 (C3AR1), CDw379 (FPR2), CD380 (LTB4R), CDw381 (GPR183), and CDw382 (F2RL1). In this article, we introduce the newly established CD nomenclature for mAbs targeting the GPCR family. We detail the quantitative expression profiles of these molecules on various subsets of leukocytes and provide validation data for these mAbs. The implications of these expression profiles are discussed for the potential therapeutic targeting of immune-mediated diseases and cancer.