title: Decreased CD40 ligand induction in CD4 T cells and dysregulated IL-12 production during HIV infection.
abstract: During HIV infection various cytokines are overproduced in early stages, whereas in advanced disease cytokines of the T helper 1 type (e.g. interferon-gamma (IFN-gamma)) are selectively deficient. During antigenic stimulation, the production of type-1 cytokines is enhanced by IL-12, secreted by antigen-presenting cells (APC) after their interaction with activated CD4 T cells. Two factors are essential in this process: priming APC with IFN-gamma and triggering the CD40 receptor on APC by CD40 ligand (CD40L). In view of the importance of this pathway, we compared its regulation in HIV-infected and control subjects. After cross-linking of the T cell receptor (TCR)/CD3 complex, the proportional expression of CD40L was similar on CD4+ T cells from controls and from patients with high circulating CD4 T counts (> 500/microl), but CD40L up-regulation was significantly reduced in patients with more advanced disease. Simultaneous triggering of the costimulatory receptor CD28 on T cells through its natural ligand CD80 partly corrected the CD40L defect in patients with intermediate CD4 T counts (200-500), but not in AIDS patients. Early production of IFN-gamma was preserved in lymphocytes from HIV+ patients. The expression of CD40 on peripheral monocytes from HIV+ subjects was increased in a disease stage-related fashion. Stimulation of mononuclear cells through cell-bound CD40L and soluble IFN-gamma induced significantly higher IL-12 in cultures from patients with > 200 circulating CD4 T cells, whereas IL-12 production was marginally decreased in cultures from patients with < 200 CD4 T cells, compared with healthy control cultures. In conclusion, our data suggest that impaired CD40L induction on CD4 T cells contributes to deficient type-1 responses through decreased IL-12 production in AIDS infection, whereas enhanced CD40-mediated IL-12 production in less advanced stages might contribute to increased levels of various cytokines in early disease
authors.affiliation: Laboratory of Immunology, Department of Microbiology, Institut of Tropical Medicine, Antwerpen, Belgium. gvanham@itg.be
authors.forename: G
authors.initials: G
authors.lastname: Vanham
authors.forename: L
authors.initials: L
authors.lastname: Penne
authors.forename: J
authors.initials: J
authors.lastname: Devalck
authors.forename: L
authors.initials: L
authors.lastname: Kestens
authors.forename: R
authors.initials: R
authors.lastname: Colebunders
authors.forename: E
authors.initials: E
authors.lastname: Bosmans
authors.forename: K
authors.initials: K
authors.lastname: Thielemans
authors.forename: J L
authors.initials: JL
authors.lastname: Ceuppens
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology / Q000378:metabolism; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D019013:CD40 Antigens / Q000378:metabolism*; D023201:CD40 Ligand; D002478:Cells, Cultured; D004768:Enterotoxins / Q000276:immunology; D015658:HIV Infections / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis*; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D051379:Mice; D016853:Muromonab-CD3 / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000276:immunology; D018089:Superantigens / Q000276:immunology; D015854:Up-Regulation / Q000276:immunology
chemical_list: D019013:CD40 Antigens; D004768:Enterotoxins; D008024:Ligands; D008562:Membrane Glycoproteins; D016853:Muromonab-CD3; D018089:Superantigens; D023201:CD40 Ligand; D018664:Interleukin-12; C026066:enterotoxin A, Staphylococcal; D007371:Interferon-gamma