Kupffer cell blockade prevents rejection of human insulinoma cell xenograft in rats

Alloantigens are recognized by T-cells in the context of both class I and class II antigen, but class II antigens predominate in the recognition of xenoantigens. Since class II molecules bind peptides derived from exogenous proteins that have been phagocytized and digested into small fragments by antigen presenting cells, in the present studies the effect of gadolinium chloride (GdCl3)-induced Kupffer cell blockade on the survival of discordant insulinoma cell xenografts was investigated. Insulinoma cells isolated by means of collagenase from human insulinoma and cultured were transplanted through the v. portae into the liver of streptozotocin-induced diabetic, male, CFY inbred rats. In the control, streptozotocin-treated rats, the decrease in blood glucose level was only transitory, in contrast with the GdCl3-pretreated diabetic rats, which remained normoglycaemic during the 2-week observation period. Histologically, in the liver and lung of rats pre-treated with GdCl3, large areas of extensively proliferating insulinoma cells were seen, whereas no insulinoma cells were seen in either the liver or the lung of diabetic-control rats, not-treated with GdCl3. These studies suggest that the Kupffer cells play significant roles in the recognition of xenoantigens and the induction of xenograft rejection. (orig.)