Ultrastructural study of peripheral blood mononuclear cells in chronic type B hepatitis

ABSTRACT

Many studies have suggested the infection of peripheral blood mononuclear cells [PBMCs] by hepatitis B virus [HBV] and its clinical implication in affecting the clinical status and persistence of the disease. However, there is still controversy concerning the mode of existence, replicative potential and cytopathological effect of the virus in these cells. In ultrastructural studies, three morphological forms of viral particles were detected in serum and hepatocytes of hepatitis B patients. However, none of these studies involved the PBMCs. In the present work, it was aimed to directly examine isolated PBMCs by transmission electronmicroscopy [TEM] to detect the various morphological forms of the virus and to verify any morphological alterations produced in the cells by the infection. PBMCs were isolated on ficoll-hypaque from heparinized blood of five patients with chronic hepatitis B [CHB] infection and subjected to conventional electronmicroscopy and immunoelectronmicroscopy [IEM]. Three healthy subjects were included as controls. Among PBMCs, many monocytes and lymphocytes showed either degenerative or apoptotic features. Dilatation of the Golgi apparatus [GA] and endoplasmic reticulum [ER] was also encountered. Some cells displayed intracytoplasmic particulate structures localized within vacuoles and appearing in various forms. One form resembled the complete virion but was larger [100 nm in diameter] and lacking the double-shell contour. Spherical HBsAg subviral forms [25-33nm in diameter] were also observed. These structures were verified as HBV particles by IEM. Our results have provided further evidence for the presence of the replicable complete virion-like particles in PBMCs. They seem to persist, replicate and induce injury to PBMCs. This may affect the clinical outcome and persistence of the infection