Unusual CD56⁺CD19^dim Cells with Natural Killer Cell Characteristics

and inflammation are major functions of NK cells [1].They consist of various heterogeneous subpopulations, each with distinct immunophenotypes and functions [2-4].Bright or dim CD56 expression, with or without CD16 expression, is immunophenotypically the hallmark of NK cells, as well as the variable expression levels of CD94-NKG2 heterodimers, members of the killer immunoglobulin-like receptor (KIR) family, and members of the natural cytotoxicity receptor (NCR) family.Classically, NK cells are classified into immature (CD56 bright , CD94 hi , CD16 -, CD57 -), mature (CD-56 dim-to-med , CD94 med , CD16 + , CD57 -), and hypermature (CD56 dim-to- med , CD94 low , CD16 + , CD57 + ) based on their expression levels of CD16, CD56, CD57, and CD94 [2, 3].Through recent studies, the diversity of NK cell subpopulations has been expanded to a remarkable degree [5, 6].Cytometry by time-of-flight (CyTOF) analyses assessing 37 parameters simultaneously have unveiled the immense diversity within NK cell subpopulations, identifying up INTRODUCTION Natural killer (NK) cells are pivotal to innate immunity.Direct cytotoxicity and cytokine secretion during infection, tissue injury,