Analysis of histiocytosis X infiltrates with monoclonal antibodies directed against cells of histiocytic, lymphoid, and myeloid lineage.

Surface markers expressed on histiocytosis X (HX) cells were studied using 18 monoclonal antibodies (McAbs) and an in situ indirect immunoperoxidase technique. Specimens of skin (five biopsies from three cases) and lymph node (one case) were studied. Our study confirmed previous findings of an OKT6+ HLA DR+ Leu 3a+ phenotype of HX cells in skin and indicated that lymph node HX cells can also have this phenotype. A mixture of cells expressing T markers/T subset, monocyte/macrophage, and killer/natural killer (K/NK) markers was also present in two cases. However, one case with an aggressive course showed no detectable HNK 1+ (K/NK) or Leu 2A (suppressor) cells in the cutaneous infiltrates and no detectable HNK 1+ lymphocytes in an affected lymph node. The significance of these findings in relation to prognosis and therapy is discussed.