The nature and significance of tumour-associated mast cells.

The role of the mast cell in tumour growth was examined in the rat with the use of a transplanted sarcoma. Mast cells were found at the periphery of the tumours and in fibrovascular trabeculae within the tumour mass. Histochemical studies showed that these cells contained an immature proteoglycan molecule, in contrast to normal mast cells. The mast cells appeared to be of the connective tissue phenotype and their local occurrence correlated with an anteroposterior difference in tumour growth. Mast cell enhancement of tumour proliferation was demonstrated by the addition of mast cells to the initial tumour inoculum and by pharmacological inhibition of mast cell degranulation.