Immunocompetent cells of the TME in head-and-neck tumors, notably HNSCC, comprise a subpopulation of CD24hi/CD38hi/CD19+ regulatory B (Breg) cells, which predominate numerically over conventional CD19+ B cells and tend to occupy the ‘borderline’ niches at the boundary of the tumor with normal tissue [76]. Here, CD19 is linked to neoplasm.