title: Leishmanial amastigote antigen P-2 induces major histocompatibility complex class II-dependent natural killer-cell reactivity in cells from healthy donors.
abstract: Innate mechanisms involving natural killer cells have been implied to play an important role in immunity against Leishmania infection. Previous studies have evaluated responses to three purified amastigote antigens, P-2, P-4 and P-8, of Leishmania pifanoi. The P-4 and P-8 antigens have been demonstrated to induce protection in mouse models, as well as to induce cellular responses in American cutaneous leishmaniasis patients. Cells from Leishmania aethiopica-infected leishmaniasis patients preferentially responded to P-8 and, to a lesser extent, to the cysteine proteinase, P-2. In this study, it is shown that cells from healthy donors, including cells from truly naïve donors (cord blood), could be stimulated to proliferation and cytokine production by P-2. The main proliferating cell types in healthy adult donors were CD16/56(+) and the CD8(+) cells. Blocking of major histocompatibility complex (MHC) class II with alpha-MHC class II antibodies markedly inhibited proliferation and interferon-gamma (IFN-gamma) production, whereas interleukin-10 production was not affected. Experimental evidence indicates that CD4(+) cells were not necessary for the proliferative and IFN-gamma responses; however, an adherent cell population was required. Furthermore, CD16/56(+) cells expressing MHC class II were expanded following P-2 stimulation. The responses to P-2 show a striking similarity to responses induced by the vaccine candidate Leishmania homologue of receptors for activated C-kinase (LACK) in healthy donors. The responses described here may not be desirable when aiming at inducing protective immune responses with a vaccine, and the implications of these results for the development of vaccines against leishmaniasis are discussed.
authors.affiliation: Microbiology and Tumour Biology Centre, Karolinska Institutet and Swedish Institute for Infectious Disease Control, Stockholm, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Nylén
authors.forename: K
authors.initials: K
authors.lastname: Maasho
authors.forename: D
authors.initials: D
authors.lastname: McMahon-Pratt
authors.forename: H
authors.initials: H
authors.lastname: Akuffo
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005312:Fetal Blood / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D016753:Interleukin-10 / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology*; D007891:Leishmania / Q000276:immunology*; D007896:Leishmaniasis / Q000276:immunology* / Q000517:prevention & control; D008213:Lymphocyte Activation / Q000276:immunology; D016052:Protozoan Vaccines / Q000276:immunology; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D017452:Receptors, IgG / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000953:Antigens, Protozoan; D000949:Histocompatibility Antigens Class II; D016052:Protozoan Vaccines; D012333:RNA, Messenger; D017452:Receptors, IgG; D016753:Interleukin-10; D007371:Interferon-gamma