CD244 overexpression indicates NK cell dysfunction and tumor progression in diffuse large B-cell lymphoma.

Background: CD244, expressed in the tumor microenvironment (TME), is associated with impaired function of natural killer (NK) and T cells; however, its role in diffuse large B-cell lymphoma (DLBCL) remains poorly understood. This study aimed to elucidate the immunological significance and regulatory mechanisms of CD244 in DLBCL. Methods: Using single-cell and bulk RNA sequencing, we analyzed CD244 expression patterns, its major intracellular adaptor molecules, and correlations with immune checkpoints, metabolic alterations, and immune activity. The clinical and biological implications of CD244 expression, including associations with clinicopathological characteristics, TME composition, prognosis, and response to immune checkpoint blockade (ICB) therapy, were investigated by integrating single-cell and bulk RNA sequencing, immunohistochemistry, and reverse transcription-quantitative polymerase chain reaction. Intercellular communication networks, key transcription factors, and somatic mutations were further evaluated to uncover regulatory mechanisms. Results: NK cells were the primary CD244-expressing population in DLBCL, co-overexpressing PDCD1, CTLA4, LAG3, TIGIT, PTGER4, and CD160. EAT2 was identified as CD244's predominant intracellular adaptor, suggesting that CD244-associated inhibitory signaling may contribute to metabolic dysregulation and immune dysfunction in NK cells. Elevated CD244 expression correlated with an immunosuppressive TME, worse clinicopathological features, poorer outcomes, and increased potential responsiveness to ICB. Furthermore, CD244 expression may be regulated by STAT3 activation in NK cells and ASXL3 mutations in tumor cells via the BTLA-TNFRSF14 pathway. Conclusions: This study highlights the critical role of CD244 in NK cell dysfunction and DLBCL progression, providing a promising target for optimizing immunotherapy.