Mast cells in acute hepatitis.

The prevalence and morphological characteristics of mast cells were studied in 41 liver biopsies from patients with acute hepatitis of different causes. In 17 of these biopsies mast cells were found both in portal tracts and sinusoids. They were mainly found in the classical and periportal types of hepatitis, and were more abundant in the later stages of the disease. Their presence was established both by staining for mast cells at light microscopic level and by electron microscopy. Two types of mast cells were found. Those in the portal tracts had the characteristics of connective tissue mast cells in other organs. The second type was the sinusoidal mast cell. These were closely associated with a variety of myeloid cells, and ultrastructural evidence suggests that they may be derived from the latter. Mast cells are considered to participate in the inflammatory response in acute hepatitis.