Antigen presentation by XXXX dermal fibroblasts: activation of resting T lymphocytes.

@entity1 @entity5041 @entity379 @entity1192 @entity1199 @entity116
We have shown that @entity1 dermal fibroblasts, exposed to @entity379 ( @entity379 ) to induce surface class II major histocompatibility complex (MHC) antigens, were capable of presenting @entity116 toxoid (TT) antigen to @entity1 TT-specific T cell clones. Antigen presentation by fibroblasts was antigen dependent, required HLA-DR expression by fibroblasts, and was MHC restricted. In contrast, we now report that @entity379 -treated fibroblasts are unable to present TT antigen to purified resting T cells obtained from the peripheral blood of TT-immune donors. In addition, although @entity379 -treated fibroblasts were able to stimulate alloreactive T cell clones, they were unable by themselves to stimulate primary allogeneic responses in resting T cells. The failure of fibroblasts to stimulate resting T cells was not due to suppressor effects by fibroblasts, because induction of TT and alloantigen responses in resting T cells by monocytes was not inhibited by the presence of fibroblasts. On the contrary, IFN-treated fibroblasts were synergistic with small numbers of monocytes in activating resting T cells. In addition, the failure of antigen presentation by fibroblasts to resting T cells was reversed by the addition of recombinant @entity1 @entity1199 ( @entity5041 ) to cultures, but not of purified @entity1 @entity1192 ). These results emphasize that the requirements for activation of resting T cells differ from those of T cell clones. Although fibroblasts can efficiently present antigen to T cell clones, antigen presentation by fibroblasts to resting T cells requires the addition of exogenous @entity1199 . It is postulated that fibroblasts differ from classical antigen-presenting cells in that fibroblasts are incapable of stimulating the production of @entity1199 in resting T cells.
