Effect of the cytokine rhTNF-alpha on the population of mast cells in the growth of MethA fibrosarcoma--a TEM study.

The aim of the present study was the ultrastructural characteristics of mast cell (MC) involved in host antitumor responses induced by local (i.t.) administration of recombinant human tumor necrosis factor alpha (rhTNF-alpha) in the primary focus of methA fibrosarcoma. MC were involved in tumor interstitium remodeling. Numerous mitochondria, well-developed RER and Golgi apparatus, clusters of polyribosomes, considerable polymorphism of granules and differentiated lamellar structures which frequently presented myelinic forms were observed after rhTNF-alpha application. In the study numerous fibres of the fibrous tissue, richly vascularized, occurred in the peripheral and intermediate tumor zones. Cluster of MC and tumor cells were seen on the border of the necrotic foci. However, proteolytic enzymes released by MC cause interstitial lysis, ensuring the place for tumor growth, and are involved in angiogenesis. Thus, it is not clear whether MC contribute to the inhibition of tumor growth or have an adjunctive role in tumor progression.