Human dendritic cells stimulate allogeneic T cells in the absence of IL-1.
Dendritic cells (DC), which express high-density HLA class II molecules, stimulate strong primary allogeneic T-cell responses via an interaction of the T-cell receptor with major histocompatibility complex (MHC) antigens (signal 1). It is not yet clear whether they also provide a second stimulus to the responding T cell in the form of the cytokine interleukin-1 (IL-1). To clarify this point, the ability of purified human tonsil DC to produce IL-1 and to stimulate allogeneic T cells was tested. No intracellular IL-1 alpha or beta was identified in DC comparable to that readily demonstrated in monocytes, and IL-1 release from lipopolysaccharide (LPS)-stimulated DC was not detected in either a biological assay for IL-1 or an ELISA assay for IL-1 beta. Furthermore, strong stimulation of allogeneic T lymphocytes by DC in the mixed leucocyte reaction (MLR) was noted to occur in the absence of IL-1 production, and this stimulation was not inhibited by polyclonal antisera to IL-1 alpha and IL-1 beta, which were known to inhibit IL-1-mediated thymocyte proliferation. Other HLA-class II-positive cell populations, namely peripheral blood monocytes and B cells, purified by methods which avoided DC contamination, were unable to stimulate allogeneic T cells with or without supplementary IL-1. We conclude that DC are very effective stimulators of T lymphocytes and that IL-1 is not required as a second signal for allogeneic T-cell responses.
McKenzie
J L
JL
Haematology Department, Christchurch Hospital, New Zealand.
Prickett
T C
TC
Hart
D N
DN
D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D006801:Humans; D007375:Interleukin-1 / Q000276:immunology* / Q000378:metabolism; D007959:Lymphocyte Culture Test, Mixed; D009000:Monocytes / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D007375:Interleukin-1