title: Lower numbers of natural killer T cells in HIV-1 and Mycobacterium leprae co-infected patients.
abstract: Natural killer T (NKT) cells are a heterogeneous population of lymphocytes that recognize antigens presented by CD1d and have attracted attention because of their potential role linking innate and adaptive immune responses. Peripheral NKT cells display a memory-activated phenotype and can rapidly secrete large amounts of pro-inflammatory cytokines upon antigenic activation. In this study, we evaluated NKT cells in the context of patients co-infected with HIV-1 and Mycobacterium leprae. The volunteers were enrolled into four groups: 22 healthy controls, 23 HIV-1-infected patients, 20 patients with leprosy and 17 patients with leprosy and HIV-1-infection. Flow cytometry and ELISPOT assays were performed on peripheral blood mononuclear cells. We demonstrated that patients co-infected with HIV-1 and M. leprae have significantly lower NKT cell frequencies [median 0.022%, interquartile range (IQR): 0.007-0.051] in the peripheral blood when compared with healthy subjects (median 0.077%, IQR: 0.032-0.405, P < 0.01) or HIV-1 mono-infected patients (median 0.072%, IQR: 0.030-0.160, P < 0.05). Also, more NKT cells from co-infected patients secreted interferon-γ after stimulation with DimerX, when compared with leprosy mono-infected patients (P = 0.05). These results suggest that NKT cells are decreased in frequency in HIV-1 and M. leprae co-infected patients compared with HIV-1 mono-infected patients alone, but are at a more activated state. Innate immunity in human subjects is strongly influenced by their spectrum of chronic infections, and in HIV-1-infected subjects, a concurrent mycobacterial infection probably hyper-activates and lowers circulating NKT cell numbers.
authors.affiliation: Division of Clinical Immunology and Allergy, University of São Paulo, São Paulo, Brazil.
authors.forename: Karina I
authors.initials: KI
authors.lastname: Carvalho
authors.forename: Fernanda R
authors.initials: FR
authors.lastname: Bruno
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Snyder-Cappione
authors.forename: Solange M
authors.initials: SM
authors.lastname: Maeda
authors.forename: Jane
authors.initials: J
authors.lastname: Tomimori
authors.forename: Marilia B
authors.initials: MB
authors.lastname: Xavier
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Haslett
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Nixon
authors.forename: Esper G
authors.initials: EG
authors.lastname: Kallas
mesh_terms: D000328:Adult; D060085:Coinfection / Q000276:immunology*; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007918:Leprosy / Q000150:complications / Q000276:immunology*; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D009166:Mycobacterium leprae; D055611:Natural Killer T-Cells / Q000276:immunology*; D055815:Young Adult