Abstract

Tumour cells from three cases of malignant histiocytosis of the intestine (MHI) have been studied immunologically and cytochemically. The cells did not form E rosettes and showed weak Fc gamma surface receptors. They contained non-specific esterase and acid phosphatase in diffuse granular distribution. In one case tumour cells showed no staining by an immunoperoxidase technique with two monoclonal anti-T cell antibodies but positive staining with a monoclonal anti-Ia-like antibody. The malignant cells from all three cases could be shown to contain alpha-1-antitrypsin. These are the first cases of MHI to have been studied in this way and the results confirm the true histiocytic--that is, monocyte/macrophage, derivation of the tumour cells in this disease.