EXPRESSION OF ADHESION MOLECULES IN LANGERHANS CELL HISTIOCYTOSIS

Expression of adhesion molecules was investigated in six biopsy specimens of Langerhans' cell histiocytosis using immunocytochemistry. Cells with Langerhans' cell histiocytosis morphology were stained for ICAM-1, for the beta-1 integrins alpha-4 (VLA-4) and alpha- 5 (VLA-5), and for the beta-2 integrins 1,FA-1. MAC-1 and p150,95. This pattern of reactivity was different from that of epidermal Langerhans' cells of the normal skin which were not immunostained. A variable number of CD68+ multinucleated giant cells was present in five biopsies. They were less reactive than the cells of Langerhans' cell histiocytosis for alpha-4 (VLA-4) and LFA- 1, were positive for MAC-1 and p150,95 and were characterized by prominent expression of the beta-1 integrins alpha-2 (VLA-2), alpha- 3 (VLA-3) and of VnR (alpha-v/beta-3). The repertoire of adhesion molecules expressed by giant cells is indicative of profound cell-matrix interactions, whereas that of Langerhans' histiocytosis cells suggests particularly active cell-cell interactions. Blood vessels of the lesions were stained for beta-1 integrins, for vitronectin receptor and for molecules involved in adhesion and trans-endothelial migration of circulating leukocytes, such as ICAM-1, VCAM-1 and E-selectin. Additional findings were the observation of CD1a+ multinucleated giant cells in a single case, suggesting a possible lineage relationship with the histiocytosis cells, and the demonstration of some Ki-67 + Langerhans' cell histiocytosis cells and CD1a+ mitotic figures in four of six cases, indicating local proliferation of Langerhans' histiocytosis cells.