We identified the major cell types comprising PBMCs, including: T cells (TC1 and TC2 clusters) characterized by CD3 and T cell receptor (TRAC) expression; B cells (BC cluster) characterized by MS4A1 (CD20) and CD19 expression; natural killer cells (NK cluster) characterized by KLRF1 expression; 2 subsets of monocytes (M14 and M16 clusters) characterized by CD14 and FCGR3A (CD16) expression, respectively; and erythrocytes (EC cluster) characterized by HBA1 (hemoglobin alpha locus 1) expression (Fig. 1D and SI Appendix, Fig. S1E). Here, CD19 is linked to breast cancer.