Human proximal tubular cells modulate allogen responses of leukocytes in vitro

The interaction between proximal tubular cells and leukocytes was examined. In co-cultures of tubular cells and allogenic leukocytes, tubular cells expressed MHC antigens and ICAM-1. A small number of leukocytes adhered to tubular cells and induced cytotoxic damage. Thus, 65% of the tubular cells were viable after co-culturing with allogenic leukocytes. These cells had low alloreactive capacity, which was not due to lack of interleukin-1 or interferon-gamma. The presence of tubular cells modulated the immune response of leukocytes by reducing the effect of mitogen by 80%, allogens by 65% and interleukin-2 by 40%. A soluble factor released in the co-cultures was a likely mediator, since addition of supernatants from co-cultures suppressed mitogen responses by 27% compared to leukocytes cultured alone. This mediator might be prostaglandin, because addition of indomethacin to co-cultures increased the growth response of leukocytes.