Percentage of CD56⁺ monocytes at neutrophil engraftment is associated with the incidence of acute graft-versus-host disease

Although several biomarkers for acute GVHD have been proposed, no definitive predictive markers are clinically available. Recent studies have shown that a specific subset of peripheral blood monocytes expresses CD56 (neural cell adhesion molecule [NCAM]), particularly under inflammatory conditions; however, their role in allogeneic HSCT remains unclear.

Single-cell RNA sequencing of peripheral blood mononuclear cells from patients with acute GVHD identified a unique monocyte subset characterized by an NCAM signature. Prospective multicolor flow cytometry analysis of peripheral blood samples revealed a transient increase in CD56⁺ monocytes at the time of neutrophil engraftment. Gene set enrichment analysis demonstrated pro-inflammatory transcriptome signatures of the CD56⁺ monocyte fraction.