THE IMMUNE REACTIVITY ROLE OF HCV-INDUCED LIVER INFILTRATING LYMPHOCYTES IN HEPATOCELLULAR DAMAGE

Liver infiltrating lymphocytes (LIL) were isolated from HCV-positive ( +) and HCV-negative (-) end-stage livers. Phenotypic analysis and func tional studies using proliferative and lymphocytotoxic assays were per formed with the isolated LIL. Two CD3+ lymphocyte populations were fou nd in LIL using FITC anti-CD3 monoclonal antibodies (mAb), One was a b right fluorescence intensity population (as in PBL), and the other dim . We calculated the number of FITC-anti-CD3 mAbs bound per lymphocyte on PBL and LV, and found 80,040 +/- 4628 and 39.615 +/- 3932, respecti vely. Therefore, HCV+ and HCV- patient PBL contained approximately twi ce the number of CD3 molecules per cell than patient CD3+ LIL. LIL als o contained approximately a threefold higher concentration of TCR alph a beta+, CD4-CD8-, and CD56,16 (NK) cells than the patient PBL. Thus, a major subset of LIL is phenotypically similar to mouse NK1.1+ ''inte rmediate'' T cells. LIL freshly isolated from HCV+ livers exhibited we ak CTL activity against EBV- or Con A-transformed lymphoblast targets infected with vaccinia-HCV recombinant virus (rHCV) or primary hepatoc yte cultured cells. However, after in vitro a coculture of LIL with rH CV, these cells developed a strong cytotoxicity for the above targets. In contrast, LIL from HCV-livers were not cytotoxic against the same targets. Histochemical studies (in situ) demonstrated that these hepat ocytes express CD95, and stains demonstrated apoptosis. The HCV+ hepat ocytes also express class I MHC molecules and ICAM-1. The addition of mAb specific for these adhesion molecules inhibited CML activity. Shor t-term cultured hepatocytes (targets) from HCV+ and HCV- patients prod uced low levels of cytokines IL-1 beta, IL-2, IL-6, TNF alpha, and IFN -gamma but a high level of IL-8. It is speculated that LIL expressing reduced numbers of CD3 molecules may even function as immune regulator s as proposed for intermediate T cells in mice.