Effects of immunoregulatory cytokines on the immunogenic potential of the cellular components of a bilayered living skin equivalent

The purpose of this study was to determine if the immunocompatibility of an allogeneic living skin equivalent (LSE) would be affected by cytokines that would be potentially present at the wound site. Specifically, the ability of interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6), or interleukin-12 (IL-12) to induce an allogeneic T cell response to "nonprofessional" antigen presenting cells (APC) was investigated in this series of experiments. Since cytokine concentrations at the wound site can vary greatly, recombinant IL-1 alpha, IL-6, and IL-12 were used over a wide range of concentrations. These cytokines were either added directly to a mixed lymphocyte reaction (MLR) culture system or used to pretreat APC prior to use in the MLR culture. The addition of IL-12, IL-1 alpha, or IL-6 into an MLR was examined as a possible means of providing the necessary costimulatory signal for functionally deficient APC, such as human keratinocytes (HK) and dermal fibroblasts (HF). While the results show that IL-1 alpha and IL-12 can significantly augment a primary allogeneic response against appropriately equipped antigen presenting cells, the same was not true for HK or HF. Further experiments showed that pretreatment of HK, HF, or human umbilical vein endothelial cells (HUVEC) with Interferon-gamma (IFN gamma) and either IL-12, IL1 alpha, or IL-6 had no significant affect on their ability to present alloantigen to immune-reactive T lymphocytes over IFN gamma-treatment alone. The data suggest that exposure of HK or HF to IL-1 alpha, IL-6, or IL-12 in combination with IFN gamma does not provide the additional signal(s) required by these cells to effectively present alloantigen to unprimed T cells. The data suggests that exposure to these immunoregulatory cytokines in the wound bed would be unlikely to affect the immunocompatibility of the LSE.