Staining of tissues from healthy human skin using anti-CD40 mAb showed very weak expression of CD40 by the endothelium, while skin involved in inflammatory disease showed marked upregulation of CD40 expression.
These cells expressed the costimulatory molecules CD86 and CD40 and stimulated allogeneic T cells, suggesting that these mononuclear cells are a population of antigen-presenting cells and that they may play a role in clearing antigen and protecting against inflammatory disease in BALB/c mice.