Co-culture of primary human tumor hepatocytes from patients with hepatocellular carcinoma with autologous peripheral blood mononuclear cells: study of their in vitro immunological interactions.

Background: Many studies have suggested that the immune response may play a crucial role in the progression of hepatocellular carcinoma (HCC). Therefore, our aim was to establish a (i) functional culture of primary human tumor hepatocytes and non-tumor from patients with hepatocellular carcinoma (HCC) and (ii) a co-culture system of HCC and non-HCC hepatocytes with autologous peripheral blood mononuclear cells (PBMCs) in order to study in vitro cell-to-cell interactions.

Methods: Tumor (HCC) and non-tumor (non-HCC) hepatocytes were isolated from the liver resection specimens of 11 patients operated for HCC, while PBMCs were retrieved immediately prior to surgery. Four biopsies were obtained from patients with no liver disease who had surgery for non malignant tumor (normal hepatocytes). Hepatocytes were either cultured alone (monoculture) or co-cultured with PBMCs. Flow cytometry measurements for MHC class II expression, apoptosis, necrosis and viability (7AAD) were performed 24 h, 48 h and 72 h in co-culture and monocultures.

Results: HCC and non-HCC hepatocytes exhibited increased MHC-II expression at 48h and 72h in co-culture with PBMCs as compared to monoculture, with MHC II-expressing HCC hepatocytes showing increased viability at 72 h. PBMCs showed increased MHC-II expression (activation) in co-culture with HCC as compared to non-HCC hepatocytes at all time points. Moreover, CD8+ T cells had significantly increased apoptosis and necrosis at 48h in co-culture with HCC hepatocytes as compared to monocultures. Interestingly, MHC-II expression on both HCC and non-HCC hepatocytes in co-culture was positively correlated with the respective activated CD8+ T cells.

Conclusions: We have established an in vitro co-culture model to study interactions between autologous PBMCs and primary HCC and non-HCC hepatocytes. This direct interaction leads to increased antigen presenting ability of HCC hepatocytes, activation of PBMCs with a concomitant apoptosis of activated CD8+ T cells. Although, a partially effective immune response against HCC exists, still tumor hepatocytes manage to escape.