Detection and Quantitation of Macrophage Infiltration Into Primary Human Tumors With the Use of Cell-Surface Markers 2

Abstract

The present study was designed to determine the presence of Fc receptor-positive cells within a series of primary nonlymphoreticular human neoplasms and to characterize them as to type. Frozen sections from 39 tumors of various histopathologic types were evaluated both qualitatively and quantitatively for Fc receptor activity by adsorption of antibody-coated sheep erythrocytes (EA). The quantity of EA adsorption varied from less than 5 to 100% of the tumor section covered. Positive sections exhibited two patterns of adsorption: focal and diffuse. Evaluation of sections exhibiting focal patterns indicated that the areas where tumor cells were concentrated failed to adsorb EA. Nevertheless, in many of the tumors, the admixture of tumor cells and Fc receptor-positive cells was significant. Of the tumors, 22 were digested enzymatically and their cell content was assessed. In each of the derived tumor cell suspensions, fewer than 5% of the cells were morphologically identifiable as lymphocytes. Similarly, morphologic analysis demonstrated few granulocytes in 20 of 22 tumors. Moreover, the percentage of Fc receptor-positive cells in the suspensions varied from 2 to 56. The Fc receptor-positive cells were characterized by nonspecific esterase staining, phagocytosis, and morphology as greater than 95% macrophages. The number of Fc receptor-positive cells in the suspensions correlated well with the degree of EA adsorption to tumor sections. Thus clearly many primary human neoplasms included in this study were infiltrated by significant numbers of macrophages.