title: Cytolytic activity of natural killer cells and lymphokine activated killer cells against hepatitis A virus infected fibroblasts.
abstract: The role of Natural Killer (NK) cells, Lymphokine Activated Killer (LAK) cells and the induction of cytokines in the hepatocellular injury of hepatitis A were studied in vitro using a 51Cr release assay in hepatitis A virus (HAV) infected MRC-5 cells (MRC-HAV). When fresh peripheral mononuclear cells (PBMC) from healthy, anti-HAV antibody (-) and (+) human donors, or patients with acute hepatitis A were used as effector cells, MRC-HAV were lysed more extensively than uninfected cells. Similarly, in models using recombinant interleukin-2 (rIL-2) pretreated PBMC from HAV antibody (-) and (+) donors or patients with hepatitis A as effector cells, MRC-HAV were lysed more extensively than uninfected MRC. Both fresh PBMC and rIL-2 pretreated PBMC from anti-HAV antibody (+) donor lysed MRC-HAV cells more effectively than PBMC collected from anti-HAV antibody (-) patients. PBMC from patients with hepatitis A during the acute phase demonstrated more severe lysis of both uninfected MRC and MRC-HAV target cells. However, MRC-HAV lysis was enhanced to a greater degree. In an attempt to identify which cells were involved in cell lysis, cytotoxicity assays were performed by separating PBMC by cell sorter using monoclonal antibodies against all T cells, NK and B-cell fractions and culturing each with supplemental rIL-2. The NK cell fraction selectively destroyed MRC-HAV, but the lytic activity of both the pan T-cell and B-cell fractions was too weak to demonstrate any significant difference. Therefore, NK-LAK cells appeared to play a more significant role in cytolysis than did T-LAK cells. Morphologic observations of cellular damage were accomplished with PBMC obtained from healthy anti-HAV antibody (+) donors. PBMC were suspended in media containing rIL-2 and incubated for 4 days on monolayers of uninfected MRC and MRC-HAV. IFN-alpha and IFN-gamma in the supernatant of the cultured media were simultaneously assayed. Severe damage to HAV-infected cells was observed. Moreover, strong induction of IFN-alpha and IFN-gamma was found with high levels measured in the supernatant. Therefore, it is likely that non-specific immune mechanisms involving NK and LAK cells play a central role in hepatocellular damage prior to the initiation of damage due to Cytotoxic T Lymphocytes (CTL).
authors.affiliation: Third Department of Internal Medicine, Mie University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Baba
authors.forename: H
authors.initials: H
authors.lastname: Hasegawa
authors.forename: M
authors.initials: M
authors.lastname: Nakayabu
authors.forename: K
authors.initials: K
authors.lastname: Fukai
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic; D005347:Fibroblasts / Q000821:virology; D006506:Hepatitis A / Q000276:immunology; D035922:Hepatitis A Antibodies; D017957:Hepatitis A Virus, Human / Q000276:immunology*; D006508:Hepatitis Antibodies / Q000276:immunology; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D015979:Killer Cells, Lymphokine-Activated / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008168:Lung / Q000821:virology*; D011994:Recombinant Proteins; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D016207:Cytokines; D035922:Hepatitis A Antibodies; D006508:Hepatitis Antibodies; D007376:Interleukin-2; D011994:Recombinant Proteins