Figure 9. Role for CD79a in reciprocal interactions between immature myeloid and tumor cells that promote tumorigenesis and metastasis.

Metastatic tumors induce the expansion of an immature myeloid cell population in bone marrow and spleen, and drive enrichment of a subpopulation that expresses elevated CD79a. An as yet unidentified CD79a ligand secreted by tumor cells activates the CD79a on the immature myeloid cells leading to signaling through Syk and BLNK and modulation of cellular phenotype in a variety of ways. These include maintainance of the immature state, upregulated expression of tumor-promoting cytokines and chemokines, increased migration, and enhanced immunosuppressive activity. This phenotypic modulation induces and/or amplifies the stimulatory effect of MDSCs on tumorigenesis and metastasis.