Exogenous interleukin-10 increased in vitro rejection of allogeneic keratinocytes.

Interleukin-10 (IL-10) is an anti-inflammatory cytokine that has been shown to alter HLA expression in some hemopoietic cells. In skin, the presenting capacity of Langerhans' cells is reduced by IL-10, but little is known about the effect of IL-10 on keratinocytes. Using in vitro experiments, we have shown that IL-10 augments the HLA-DR expression of keratinocytes in the presence of interferon gamma. The increase in HLA-DR expression increased the stimulation and proliferation of allogeneic peripheral blood mononuclear cells, which in turn increased the in vitro rejection of allogeneic keratinocytes. Therefore exogenous application of IL-10 to cultured keratinocytes augments the rejection by allogeneic peripheral blood mononuclear cells in vitro conditions rather than having the suspected protective effect.