Langerhans' cells and macrophages in eosinophilic granuloma. An enzyme-histochemical, enzyme-cytochemical, and ultrastructural study.

Biopsy material of six patients with eosinophilic granuloma (EG) was investigated by electron microscopic and enzyme-histochemical methods for acid phosphatase (AcP), leucyl-beta-naphthylamidase (LA), adenosine triphosphatase, and alpha-naphthyl-acetate esterase (NE). Paraplast sections were used for demonstration of lysozyme with an immunoperoxidase method. Results of staining for these different enzymes suggested the existence of two separate sets of histiocytic cells: one type with "dot-like" AcP staining and negative for NE and lysozyme; and the other with diffuse AcP staining, positive for NE and lysozyme, and often showing signs of phagocytosis. The first type presumably represented Langerhans' cells and also often showed positive staining for LA. Macrophages were generally negative for LA. Electron microscopic study confirmed the impression gained from enzyme-histochemical studies. No intermediate cell types between Langerhans' cells and genuine macrophages were seen. From these results it is concluded that in EG no transformation exists between Langerhans' cells and macrophages. The latter are presumably of reactive nature.