Abstract
Local free cell (eosinophils and macrophages) and extracellular (acid mucopolysaccharides) reactions were studied by histochemical techniques in 72 primary lung cancers (Group A), 17 pulmonary metastases and 5 lung tumours of unknown origin (Group B). Strong cellular reactions were more frequent in Group A than in Group B, whereas extracellular reactions were more frequent in Group B than in Group A. In both groups the degrees of eosinophilic infiltration and accumulation of acid mucopolysaccharides tended to be negatively correlated. In contrast, macrophages and eosinophils showed a positive correlation in the primary cancers, but none in the other tumours. The extracellular material had physical and chemical properties (solubility, affinity to stains and degradability by enzymes) of the sulphated acid mucopolysaccharides. From its distribution it appeared to be derived from fibroblasts and/or tumour cells.