EXPRESSION OF GM-CSF RECEPTOR BY LANGERHANS CELL HISTIOCYTOSIS CELLS

Langerhans' cell histiocytosis (LCH) is characterized by the prolifera tion of large mononucleated cells containing Birbeck granules and expr essing CDla. Recent studies have demonstrated that LCH is a clonal pro liferation; however, its aetiology is still unknown. Growth and differ entiation of bone-marrow-derived cells are controlled by cytokines. Th e proliferation, differentiation and activation of normal Langerhans c ells are controlled by granulocyte/macrophage colony-stimulating facto r (GM-CSF) in vitro. Therefore, GM-CSF could be implicated in the path ogenesis of LCH. Indeed, LCH cells contain GM-CSF, and children with d isseminated LCH have an elevated GM-CSF serum level. As a cytokine onl y acts on cells expressing a specific receptor, we investigated the pr esence of GM-CSF receptor on LCH cells. Fourteen frozen tissue samples from children with LCH were studied by in situ immunohistochemistry w ith two mouse monoclonal antibodies specific for the a chain of the GM -CSF receptor (CDw116). LCH cells of all the samples were positively s tained with both antibodies. This study suggests that GM-CSF may be a growth factor for LCH cells.