title: Lymphokine-activated killer cell regulation of T-cell-mediated immunity to Candida albicans.
abstract: Monocytes are important accessory cells in the activation of T cells for specific antigen recognition yet little is known of their regulation. We demonstrated here that interleukin-2 (IL-2)-induced human lymphokine-activated killer (LAK) cells can inhibit monocyte antigen presentation, depending on the state of differentiation of the monocytes. Adherent monocytes cultured for 4 days in medium or granulocyte-macrophage colony-stimulating factor (GM-CSF) were found to equally process and present intact Candida albicans to autologous Percoll gradient-isolated T cells, as measured by [3H]thymidine uptake. However, only the GM-CSF-cultured monocytes were functionally inhibited by autologous 4-day IL-2-induced LAK cells. Even soluble candidal cell wall mannoprotein antigens could not be presented by these monocytes after exposure to LAK cells. Pretreatment of these monocytes with LAK cells for 1 h, followed by subsequent removal of the nonadherent LAK cells, was sufficient to cause significant inhibition, with maximal inhibition observed after 4 h. Northern (RNA) blot analysis indicated that mRNA expression for IL-1 alpha and IL-1 beta in response to C. albicans stimulation was also down-regulated in GM-CSF-cultured monocytes exposed to LAK cells. Interestingly, freshly isolated, Percoll gradient-purified large granular lymphocytes did not suppress antigen presentation in GM-CSF-treated monocytes. Another important finding was the inability of LAK cells to suppress the ability of freshly isolated or gamma interferon-cultured monocytes, which are resistant to LAK cell-mediated lysis, to present antigen to T cells. In contrast, IL-3 was similar to GM-CSF in inducing LAK cell susceptibility in monocytes. Taken together, these results indicated that IL-2 can induce LAK cells to down-regulate antigen presentation function in a select set of monocytes that have been activated by colony-stimulating factor (GM-CSF and IL-3) but not by gamma interferon. LAK cells may therefore play an important role in regulation of monocytes and their function, depending on their differentiation state.
authors.affiliation: Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, Tampa 33612.
authors.forename: S
authors.initials: S
authors.lastname: Wei
authors.forename: D K
authors.initials: DK
authors.lastname: Blanchard
authors.forename: S
authors.initials: S
authors.lastname: McMillen
authors.forename: J Y
authors.initials: JY
authors.lastname: Djeu
mesh_terms: D000938:Antigen-Presenting Cells / Q000502:physiology; D002176:Candida albicans / Q000276:immunology*; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D015536:Down-Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000096:biosynthesis; D007376:Interleukin-2 / Q000494:pharmacology; D015979:Killer Cells, Lymphokine-Activated / Q000502:physiology*; D009000:Monocytes / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D016207:Cytokines; D007375:Interleukin-1; D007376:Interleukin-2; D012333:RNA, Messenger; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor