Mast Cells Influence the Proliferation Rate of Myeloma Plasma Cells

In multiple myeloma (MM), mast cells (MCs) modify bone marrow microenvironment. In order to estimate whether MC density (MCD) in active MM bone marrows relates to the proliferative activity of plasma cells, we estimated in 42 patients MCD, microvascular density (MVD), and the Ki-67 proliferation index (PI) (immunohistochemical expression of tryptase, CD31, and Ki-67). MCD correlated with Ki-67 PI (p < .001), suggesting the important participation of MCs in MM biology and growth; MCs enhance angiogenesis and produce cytokines with growth effects on myeloma cells. Therefore, MCs could be valuable targets for therapeutic interventions.