Lysis of blood platelets by human osteosarcoma cells in vitro.

The in vitro interactions between human osteosarcoma (HOS) cells and platelets were studied in real time using video-enhanced microscopy. Interference reflection techniques showed that platelets were lysed within minutes after contacting HOS cells that had been treated with interferon-gamma. Untreated HOS cells lysed platelets less efficiently. Platelet lysis depended on platelet-tumor cell contact and on extracellular Ca2+. A number of possible mechanisms were excluded. Lysis of platelets in proximity to tumor cells can provide these with growth factors and thereby contribute to the metastasis-enhancing effect of platelets.