IMMUNOHISTOCHEMICAL CHARACTERIZATION OF HEPATIC LYMPHOCYTES IN ACUTE HEPATITIS-A, HEPATITIS-B, AND HEPATITIS-C

The distinctive histologic findings in acute hepatitis A, B, and C sug gest that different immunological mechanisms are involved in the patho genesis of these diseases. This study was undertaken to define the imm une response in each type of acute hepatitis by identification of the intrahepatic lymphocyte subsets. Thirty paraffin-embedded liver biopsy specimens from 10 patients with acute hepatitis A, 10 patients with a cute hepatitis B, and 10 patients with acute hepatitis C were evaluate d. Immunohistochemical staining was performed by the indirect immunope roxidase technique using the follow ing monoclonal or polyclonal antib odies: CD45RO, CD20-cy, CD57, and Mac387. Inflammatory infiltrates var ied from specimen to specimen. However, CD45RO(+) memory T cells were the predominant infiltrating mononuclear cells in all specimens. In th e portal areas, CD45RO(+) memory T cells were the most prominent in AH C, followed by AHA and AHB, and the difference between AHC and AHB was statistically significant. CD20-cy(+) B cells were seen mainly in the portal areas, and were significantly less common in AHB than in AHA a nd AHC. In addition, the ratio of CD20-cy(+) B cells to CD45RO(+) memo ry was significantly lower in AHB than in the other types of acute hep atitis. The necrotic areas in all specimens contained mainly CD45RO(+) memory cells in association with a few CD57(+) NK and T cells or CD20 -cy(+) B cells. Our study revealed differences of the intrahepatic lym phocyte subsets among the various types of acute hepatitis, but the me aning of these differences is presently unknown. Therefore, further st udies are required to fully elucidate the mechanism of the immune resp onse in acute hepatitis.