Allogeneic MHC class I ligands and their role in positive and negative regulation of human cytotoxic effector cells

Resistance to cytotoxic chemotherapy is induced by NK cells in non-Hodgkin's Lymphoma Cells

It is known that B lymphoma cells are sensitive to cytotoxic chemotherapy, but primary or secondary chemoresistance frequently occurs and is the major cause of death in these patients. However, the mechanisms by which lymphoma cells acquire resistance to cytotoxic drugs are not fully understood. Recently, it was reported that B cells secrete immunoglobulin and produce cytokines after interacting with NK cells, thus indicating the importance of NK/B interactions. In this study, we investigated the mechanism of resistance to cytotoxic chemotherapy induced in cocultures of NK cells and Raji cells. Normally, Raji cells are doxorubicin-sensitive, but Raji cells cocultured with NK cells become doxorubicin-resistant. In addition, we detected the upregulation of CD69 and CD70 on Raji cells cocultured with NK cells, suggesting that Raji cells are activated by NK cells. We also found that the resistance of Raji cells to doxorubicin increased when they had been treated with NK cell coculture supernatant. Furthermore, boiled culture supernatant did not inhibit doxorubicin-mediated cell death, indicating that soluble factors are involved. Finally, we confirmed that NK cells produce TNF alpha, and that doxorubicin-sensitive Raji cells become doxorubicin-resistant after TNF alpha treatment. Taken together, these results suggest that B lymphoma cell resistance to doxorubicin-mediated cell death is induced by coculture with NK cells, because of TNF alpha secretion.

Additive inhibition of dendritic cell allostimulatory capacity by alcohol and hepatitis C is not restored by DC maturation and involves abnormal IL-10 and IL-2 induction

BACKGROUND

Excessive alcohol use results in impaired immunity, and it is associated with increased incidence and progression of chronic hepatitis C virus (HCV) infection. Here we investigated the effects of HCV infection and alcohol on myeloid dendritic cells (DC) that are critical in antiviral immunity.

METHODS

Immature and mature DCs were generated from monocytes of chronic HCV infected patients (HCV-DC) and controls (N-DC) with IL-4 plus granulocyte-macrophage colony stimulating factor (GM-CSF) in the presence or absence of alcohol (25 mM). DC allostimulatory capacity was tested in mixed lymphocyte reaction (MLR) and cytokine production by ELISA.

RESULTS

Allostimulatory capacity of HCV-DCs was reduced compared to N-DCs and it was further inhibited by alcohol treatment (p < 0.01). MLR was also decreased with alcohol-treated N-DCs. DC phenotypic markers and apoptosis were comparable between HCV-DCs and N-DCs irrespective of alcohol treatment. However, HCV-DCs and alcohol-treated N-DCs exhibited elevated IL-10 and reduced IL-12 production. Reduced MLR with HCV-DCs and its further inhibition by alcohol coexisted with decreasing IL-2 levels (p < 0.017). DC maturation partially improved but failed to fully restore the reduced allostimulatory function of either alcohol-treated or alcohol-naïve HCV-DCs (p < 0.018).

CONCLUSIONS

Alcohol and HCV independently and together inhibit DC allostimulatory capacity, increase IL-10, reduce IL-12 and IL-2 production that cannot be normalized by DC maturation. HCV and alcohol interact to modulate innate and adaptive immune responses via dendritic cells.