Human bone marrow mast cells in systemic mast cell disease. Ultrastructure and evaluation of fixation and staining techniques.

In a case of systemic mast cell disease with moderate bone marrow involvement, we studied the sensitivity of mast cell cationic dye-binding to formaldehyde fixation, as well as the mast cell ultrastructure, so as to determine whether these cells possess characteristics of mucosal mast cells. This histochemical method has proved to be one of the few which reveal heterogeneity of the mast cells in human intestine. Even though rat bone marrow mast cells have been shown to belong to the mucosal mast cell compartment, we have found no difference in mast cell counts in samples fixed either in formaldehyde or Carnoy's fixative. The ultrastructure did not show major differences with cutaneous mast cells. A few cells presented two nuclei, suggesting mitotic division of mature mast cells in bone marrow.