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Role of the transfer of metabolites from hepatocytes to splenocytes in the suppression of in vitro antibody response by dimethylnitrosamine

1988; Elsevier BV; Volume: 37; Issue: 14 Linguagem: Inglês

10.1016/0006-2952(88)90039-1

1873-2968

Kim Dong-Hyun, Kyu‐Hwan Yang, Kirk W. Johnson, Michael P. Holsapple,

Drug-Induced Hepatotoxicity and Protection

The metabolism and subsequent immunosuppressive effects of dimethylnitrosamine (DMN) were investigated in mixed cultures of mouse hepatocytes and mouse splenocytes. Hepatocytes were shown to activate DMN to an immunosuppressive form that caused the suppression of the in vitro antibody response to the T-dependent antigen, sheep erythrocytes (SRBC). A significant increase in the binding of DMN metabolites to trichloroacetic acid (TCA) precipitable material in splenocytes was induced when 94 μM [14C-methyl]DMN was added to the co-culture medium, indicating that reactive intermediates of DMN were transferred from hepatocytes to splenocytes and resulted in alkylation of macromolecules in splenocytes. The amount of [14C]DMN bound to TCA precipitable material in splenocytes increased in a time-dependent manner up to 4 hr of incubation. Aminoacetonitrile (AAN), a high-affinity DMN demethylase inhibitor, reversed the suppression by low concentrations of DMN (0.5 to 5 mM), but not by high concentrations of DMN (>5 mM). AAN also inhibited the binding of [14C]DMN to both hepatocytes and splenocytes. These results suggest that reactive metabolites of DMN are released from hepatocytes and that the suppression of the antibody response by DMN is mediated via these reactive intermediates.