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Membrane-bound IgG and lymphocytotoxic activity of total, T-enriched and T-depleted lymphocytes, using autologous hepatocytes have been evaluated in: (a) 31 patients with chronic active hepatitis (CAH) (six autoimmune and 25 hepatitis B virus - HBV-related); (b) five patients with inactive alcoholic cirrhosis; and (c) nine subjects with normal hepatic histology. Lymphocytotoxicity was positive in 83% of autoimmune CAH and 68% of HBV-related cases; it was confined to the T-depleted subpopulation in the first group, while it was present in both the T-enriched and T-depleted subpopulations in 81% of HBV-related cases. Membrane-bound IgG was present in 58% of group (a) and in none of the other groups. A linear pattern was found in four out of five autoimmune CAH patients with positive lymphocytotoxic activity. The autoimmune patient with lymphocytotoxic activity within the normal range did not show any membrane fluorescence. Among HBV-related CAH patients, 13 presented a granular pattern, two an associated granular and linear pattern and ten were negative. These data suggest that different lymphocytotoxic mechanisms are involved in the two forms of CAH studied.

The presence, in chronic active hepatitis (CAH) patients, of an inflammatory infiltrate basically composed of T lymphocytes suggested the hypothesis that these lymphocytes could play a role in the pathogenesis of the disease. The aim of this study has been to characterize, in a group of carefully selected CAH patients, the liver-infiltrating T lymphocyte, utilizing commercial monoclonal antibody (anti-Leu 1, anti-Leu 2a, anti-Leu 3a) and 5/9 monoclonal antibody that recognizes a further lymphocyte subset within T4 cells. Our data show that both T4 positive subpopulation and T8 positive subpopulation are represented in the infiltrate in the same ratio; furthermore the distribution of 5/9 positive lymphocytes is prevalent where the infiltrate is mainly composed of T8 positive lymphocytes. Moreover, there is a positive correlation between 5/9 positive cells in the liver and GPT and the patients with high percentages of infiltrating 5/9 positive lymphocytes show a low T4/T8 ratio with respect to patients with low percentages of 5/9 positive cells. These data support the hypothesis that 5/9 positive lymphocytes may present an inducer role on cytotoxic cells.

We investigated inhibitory effect of various monoclonal antibodies on T-cell-mediated cytotoxicity against autologous hepatocytes in 24 patients with hepatitis B surface antigen/hepatitis B e antigen (HBsAg/HBeAg)-positive chronic active hepatitis. A significant reduction of cytotoxicity index occurred after preincubation of T lymphocytes with anti-Leu 7 (killer-natural killer cells), D1/12 (Ia-positive cells), 5/9 (restricted helper/inducer cells), and MLR4 ("activated" and radiosensitive helper cells) monoclonal antibodies (MAb). Anti-Leu 2a (cytotoxic/suppressor cells) and anti-Leu 3a (helper/inducer cells) MAb did not affect cytotoxic activity. This finding supports the hypothesis that the T cytotoxic reaction in this in vitro system is probably due to two mechanisms: first, spontaneous cell membrane cytotoxicity sustained by anti-Leu-7-positive lymphocytes; and second, specific cytotoxicity mediated by activated Ia-positive cells. We also found that the presence of helper/inducer cells (5/9 positive) appears to be a prerequisite for the cytotoxic reaction.

The relative distribution of T lymphocyte subsets, as defined by the monoclonal antibodies OKT, was determined by cytofluorimetric analysis in peripheral blood and in cells isolated from liver biopsies of 31 patients with chronic active hepatitis (CAH). The percentage of peripheral blood lymphocytes binding OKT8 (directed against cytotoxic/suppressor T cells) was found to be elevated in patients with HBsAg and HBeAg positive chronic active hepatitis. Patients with CAH who had seroconverted to anti-HBe, had an increased number of OKT3-positive cells in their blood, which was directed against a common T cell surface antigen, associated with a decreased number of OKT8 positive cells. Lymphocytes isolated from liver biopsies of patients with CAH presented a general increase of OKT8-positive cells associated with a decreased number of OKT4-positive (helper/inducer) T cells. It is likely that OKT8-positive cells found in liver biopsies represent cytotoxic T cells directed against either viral or liver cell determinants.

Defects in T lymphocyte subpopulations and in the functional characteristics of such cells have been thought to play a role in the evolution of chronic hepatitis B, but the precise nature of the alterations and their significance remains unresolved. We studied lymphocyte subsets in 27 patients with chronic hepatitis B utilizing standard monoclonal antibodies including Leu 1,2a,3a,7 and D1/12 (against the common determinant of the Dr molecule), as well as a newly described monoclonal antibody, "5/9," which is thought to characterize a unique subpopulation of T4 cells with specific helper/inducer function. These results were compared with those obtained using the autologous mixed lymphocyte reaction assay for the same patients in order to further delineate the lymphocyte alterations in chronic hepatitis B. A significant reduction in the mean number of Leu 3a (T4) positive cells was observed as well as a reduction in the number of 5/9 positive cells. These changes were most evident in those positive for HBeAg in serum. Reduction in Leu 3a cells was associated with a reduced autologous mixed lymphocyte reaction assay response, and was most marked in the HBeAg-positive individuals. These findings suggest that HBeAg-positive patients in whom active viral replication is occurring have a defect in T lymphocyte number and function, which may be due in part to reduced 5/9 positive cells. These alterations may be related to the persistence of virus in chronic active hepatitis B patients.