Properties of lymph-borne (veiled) dendritic cells in culture. II. Expression of the IL-2 receptor: role of GM-CSF.

Fresh lymph-borne (veiled) dendritic cells (L-DC) in the rat are almost totally negative for the interleukin-2 (IL-2) receptor detected by the monoclonal antibody (mAb) MRC OX39. After 16 hr culture more than 90% of L-DC are OX39 positive, and increased levels of expression can be seen within 5 hr culture. In cultures of L-DC and allogeneic lymphocytes. L-DC appear to express the IL-2 receptor more rapidly than lymphocytes. The intensity of labelling of L-DC is variable but maximal levels are similar to those seen on lymphoblasts. Culture in the presence of concanavalin A (Con A)-stimulated spleen cell supernatants or recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) results in a more rapid and intense expression of the IL-2 receptor by L-DC. L-DC cultured following rigorous T-cell depletion, or derived from athymic rats also express the IL-2 receptor after culture with GM-CSF. Cultured, but not fresh, L-DC bind iodinated recombinant IL-2 in a dose-dependent manner and binding is inhibited by excess unlabelled ligand. The amount of IL-2 bound varies but maximal amounts are similar to those bound by lymphoblasts. Following intravenous endotoxin injection, a large proportion of freshly collected L-DC express the IL-2 receptor and the number of L-DC released into the lymph is increased. An antibody to the IL-2 receptor which blocks an allogeneic MLR has no effect on a xenogeneic MLR using rat L-DC as stimulators and mouse lymphocytes as responders.