CD81 and cancer: Moreover, although metastases were infiltrated by Mac Isg20 and Mregs, macrophages in the primary tumor were mostly of the Mac Cd81 population (Fig. 2J), expressing elevated levels of complement system genes (C1qa/b/c, Fcna), MHC-II (H2-Ab1, Cd74, Cd81), and Ccl8, which has been demonstrated as enriched in breast cancer tumor-associated macrophages (TAM), and supporting cancer cell dissemination (Fig. 2K and L; ref. 33).