CHARACTERIZATION OF CELLS CONTAINING FACTOR-XIII SUBUNIT A IN BENIGN AND MALIGNANT BUCCAL LESIONS

In the present study, the distribution pattern and characteristics of cells containing Factor XIII subunit a (FXIII A) have been studied in benign and malignant lesions of human buccal mucosa. Tissues from four irritation fibromas and three squamous cell carcinomas were studied b y means of double immunofluorescent staining techniques in which the d etection of FXIII A was combined with a reaction with CD14 (recognizin g a monocyte/macrophage differentiation marker antigen), Mac 387 (reac ting with a special subset of macrophages), anti-HLA-DR, Ki-M7 (labell ing phagocytosing macrophages) or Ki-67 (visualizing a nuclear antigen associated with cell proliferation) monoclonal antibodies. FXIII A wa s detected in cells of the connective tissue stroma in both benign and malignant buccal lesions. The number of these FXIII A-reactive cells (FXIII A(+) cells) increased considerably in the tumour tissues, in pa rticular in those surrounding tumour cell clusters. FXIII A(+) cells s cattered in the fibromatous tissues were spindle-shaped, whereas in th e tumour stroma, large stellate cells predominated, and round cells we re likewise labelled around blood vessels. FXIII A(+) cells were label led with CD14 and Ki-M7 in both fibromatous and tumoural buccal mucosa ; however, they failed to show any reaction with Ki-67. FXIII A(+) cel ls accumulated in the tumour stroma reacted for HLA-DR as well. These results indicate that in both the benign and malignant buccal lesions FXIII A is contained in a subpopulation of tissue macrophages, which r epresents a monocyte-derived (CD14(+)) and phagocytosing (Ki-M7(+)) ce ll population. The accumulation of the FXIII A(+) cells in the tumour stroma is believed to be a result of direct migration from the circula ting blood. The FXIII A(+) cells of the tumour stroma may be actively involved in both antigen presentation and matrix remodelling during tu mour progression.