The upregulation of IgM+IgD+- and IL-10+-expressing CD19+CD20+ B cells, CD19+CD20+CD5+CD1d+ Bregs, and IL-10+- and IgM+-expressing CD19+CD20+CD27+IgD+ NS MBCs in the blood of patients with MASLD strongly correlated with the murine MASLD data. Here, CD19 is linked to metabolic dysfunction-associated steatotic liver disease.