MS4A1 and melanoma: For the melanoma-associated B-cells panel, subpopulations were then classified as: (i) Total B cells (CD19+CD20-, CD19+CD20+ and CD19-CD20+ cells), (ii) Plasmablasts (CD19+CD20- CD138- cells), (iii) Plasma cell-like (CD19+CD20–CD138+ cells), and (iv) Mature Plasma Cells (CD19-/+CD20-CD138+ cells), as previously described [33].