title: Membrane-associated IL 1-like activity on rat dendritic cells.
abstract: The secretion of interleukin 1 (IL 1) by rat dendritic cells (DC) was studied in relation to their ability to induce the production of interleukin 2 (IL 2) and to induce IL 2 responsiveness. IL 1 (or IL 1-like activity) was measured by its capacity to enhance IL 2 production by EL4 cells. In contrast to peritoneal exudate cells (PEC) or splenic adherent cells, DC from thoracic duct lymph (TD-DC) or from spleen did not secrete detectable amounts of IL 1 on stimulation with LPS/Silica. However, TD-DC and splenic DC were able to enhance IL 2 production by EL4 cells directly, and were only two times less effective than PEC. By preventing cell-to-cell contact between stimulator cells and EL4 cells, it was demonstrated that most of the IL 2-inducing activity of TD-DC and PEC was associated with the cell membrane. Treatment with 1% paraformaldehyde (PFA) to abolish metabolic activity resulted in a 50% decrease (or inactivation) of IL 2-inducing activity of TD-DC in the EL4 assay. Moreover, UVB-irradiation (300 mJ/cm2) of TD-DC, which has been described to inhibit the release of IL 1 by macrophages, caused a 70% decrease in IL 2-inducing activity. In a primary allogeneic mixed leukocyte reaction, neither PFA-treated TD-DC nor UV-irradiated TD-DC were able to induce T cell proliferation or IL 2 production. The cells were, however, able to induce IL 2 responsiveness, i.e., T cell proliferation in the presence of excess human recombinant IL 2. The finding that IL 1 enhanced T cell responses to PFA-treated or UV-irradiated TD-DC in the absence and in the presence of excess IL 2 indicates that loss of stimulatory activity of TD-DC may be due in part to loss or inactivation of IL 1. These results suggest that membrane-associated structures, that are identical to or mimic IL 1, are involved in the activation of T cells by DC.
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology*; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology; D007375:Interleukin-1 / Q000276:immunology*; D007376:Interleukin-2 / Q000096:biosynthesis; D008208:Lymphatic System / Q000166:cytology / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D008264:Macrophages / Q000276:immunology; D051381:Rats; D011919:Rats, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D007375:Interleukin-1; D007376:Interleukin-2