Immunohistochemical detection of granulocyte/macrophage colony-stimulating factor in Langerhans' cell histiocytosis.

Granulocyte/macrophage-colony stimulating factor (GM-CSF) induces in vitro activation of Langerhans' cells. The association of GM-CSF and tumour necrosis factor alpha (TNF alpha) induces the differentiation of Langerhans' cells from CD34 positive haematopoietic progenitors. Intradermal administration of recombinant GM-CSF is associated with local accumulation of Langerhans' cells. We investigated the presence of GM-CSF in tissue samples of 10 patients with Langerhans' cell histiocytosis. Four patients had skin involvement, three had bone and three had diffuse disease. Eight normal skin samples were analysed as controls. Immunohistochemistry was performed on frozen tissue samples with two specific monoclonal antibodies directed against two different epitopes of GM-CSF. We detected GM-CSF in all the histiocytosis tissue samples. The GM-CSF was detected within the cytoplasm of all the tumoral Langerhans' cells. We did not find GM-CSF in any other cell type. These results suggest that GM-CSF may be implicated in the pathogenesis of Langerhans' cell histiocytosis.