Mast cells in Whipple's disease.

Abundant degranulating mast cells were observed during an ultrastructural study of jejunal biopsy from an untreated patient with Whipple's disease. Some of these cells were observed in intimate contact with macrophages containing bacteria in various stages of disintegration. Thereafter bacilli were often seen within the cytoplasm of mast cells, enclosed within vacuoles. These findings are suggestive of a cooperation between mast cell and macrophage in the defence of the organism against Whipple's bacillus.