Epidermal Langerhans cells in myelodysplastic syndromes are abnormal

The myelodysplastic syndromes (MDS) represent clonal disorders of the hematopoietic stem cell that are associated with quantitative and qualitative disturbances of the peripheral blood cells and a high risk for the transition to overt leukemia. As epidermal Langerhans cells (LC) are bone-marrow-derived cells, we were interested to see whether they are altered in patients with MDS. Epidermal sheets were prepared from biopsies taken from the thighs of nine patients with MDS and five control persons and processed for immunoperoxidase staining of CD1a antigens. The density and morphology of CD1a+ cells (i.e., LC) was evaluated by visual assessment as well as automatic image analysis. The density of LC was reduced in seven of nine patients (range, 30-75% of normal), whereas the morphology of LC appeared to be altered in all MDS patients in that the LC displayed large and bizarre cell bodies with only a few and often abnormally long dendrites. The HLA-DR expression by LC was not altered, as shown by double immunofluorescence staining of CD1a and HLA-DR antigens. Ultrastructurally, LC again appeared enlarged and often presented with bizarre nuclei, yet displayed no other abnormalities. Our findings suggest that LC are abnormal in MDS and might even indicate a more wide-spread involvement of the dendritic cell lineage in this syndrome.