title: Cluster formation of canine dendritic cells and lymphocytes is calcium dependent and not inhibited by cyclosporine.
abstract: Canine peripheral blood mononuclear cells (PBMC), dendritic cells (DC), and lymphocytes either alone or in combination were cultured with concanavalin A (ConA), calcium ionophore, and phorobol-12-myristate-13-acetate (PMA), and examined for lymphocyte/DC cluster formation and lymphocyte proliferation as determined by thymidine uptake. ConA- or calcium ionophore-stimulated proliferation of PBMC required the presence of normal DC, and was preceded by cluster formation of DC and lymphocytes. PMA-triggered proliferation was not preceded by cluster formation but also required the presence of normal DC. The presence of ultraviolet (UV)-irradiated rather than normal DC did not permit ConA-, calcium ionophore-, or PMA-triggered lymphocyte proliferation. Addition of interleukin 2 (IL-2) to cultures of lymphocytes and UV-irradiated DC restored responsiveness to PMA, suggesting that a decrease in cytokine production was the central event in UV-induced accessory cell inhibition. Cyclosporine, known to interfere with IL-2 release and responses, completely blocked both ConA- and PMA-induced lymphocyte proliferation but did not interfere with ConA-triggered cluster formation. Verapamil blocked both cluster formation and proliferation. These data show that DC/lymphocyte cluster formation is Ca2+ dependent and cannot be inhibited by cyclosporine. The data show, furthermore, that in agreement with findings in other species, triggering of canine lymphocytes by lectins and phorbol esters follows distinct pathways.
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, Washington 98104.
authors.forename: J
authors.initials: J
authors.lastname: Aprile
authors.forename: L
authors.initials: L
authors.lastname: Gerhard-Miller
authors.forename: H J
authors.initials: HJ
authors.lastname: Deeg
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D003208:Concanavalin A / Q000494:pharmacology; D003524:Cyclosporins / Q000494:pharmacology*; D003713:Dendritic Cells / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D004285:Dogs; D008213:Lymphocyte Activation / Q000187:drug effects*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D003524:Cyclosporins; D003208:Concanavalin A; D000001:Calcimycin; D014700:Verapamil; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium