Squamous cell carcinoma: infiltrating monocyte/macrophage subpopulations express functional mature phenotype.

Biopsies from 26 patients with advanced stage squamous cell carcinoma of the head and neck were investigated to determine the intensity of the inflammatory cellular infiltrate and the expression of leucocyte antigens. Mononuclear cell infiltration varied considerably between the individual patients and also within the tumour. Tumour-infiltrating cells consisted mainly of T lymphocytes and monocytes (Mo)/macrophages (M phi). Staining procedure with monoclonal antibodies (moabs) against Mo/M phi revealed different clusters of antigen expression: (1) moabs 27E10 and a-CD35 detected a subgroup of Mo/M phi with particular staining of perivasal Mo; (2) moab a-CD1 stained preferentially cells in tumour cell clusters; (3) moabs that reacted with cells of either typical M phi or dendritic morphology throughout the tumour-tissue: a-Fc gamma receptor I-III, a-class II antigens, a-CD4, Rm3/1, a-CD36 and 25F9. Thus, the majority of tumour-infiltrating mononuclear phagocytes were found to possess a rather mature phenotype. The number of Mo/M phi with mature phenotype within the tumours correlated with T lymphocyte infiltration in the tissue.