Immunohistochemical detection of cells positive for colony-stimulating factor 1 in lymph nodes from reactive lymphadenitis, and Hodgkin's disease.

Colony-stimulating factor 1 (CSF-1) is a cytokine involved in hematopoiesis and perhaps more importantly in the early stages of immunological defense mechanisms. Although numerous studies of in vitro CSF-1-producing cells have been published, in vivo data is totally lacking. According, we performed immunohistochemical detection of CSF-1-positive cells on frozen sections of reactive lymphadenitis (three cases) and Hodgkin's disease (13 cases) lymph node biopsies, using as antibody a highly specific polyclonal rabbit antiserum prepared in our laboratory. Endothelial cells from high endothelial venules and most fibroblasts were positive in all cases (reactive lymphadenitis and Hodgkin's samples), and most lymphocytes in interfollicular T cell areas showed faint granular positivity in reactive lymphadenitis lymph nodes. Hodgkin and Reed-Sternberg cells were positive in all cases tested, although staining intensity was highly variable and the percentage of positive cells differed from case to case. These data from in vivo biopsies confirm previous results for in vitro CSF-1 production by endothelial cells, fibroblasts, T lymphocytes, and Hodgkin cell lines. They are consistent with the role of this cytokine in immune response and raise the question of its significance in Hodgkin's disease.