A secreted protein from the human hookworm necator americanus binds selectively to NK cells and induces IFN-gamma production.
Parasitic helminths induce chronic infections in their hosts although, with most human helminthiases, protective immunity gradually develops with age or exposure of the host. One exception is infection with the human hookworm, Necator americanus, where virtually no protection ensues over time. Such observations suggest these parasites have developed unique mechanisms to evade host immunity, leading us to investigate the role of the excretory/secretory (ES) products of adult N. americanus in manipulating host immune responses. Specifically, we found that a protein(s) from ES products of adult N. americanus bound selectively to mouse and human NK cells. Moreover, incubation of purified NK cells with N. americanus ES products stimulated the production of augmented (4- to 30-fold) levels of IFN-gamma. This augmentation was dependent on the presence of both IL-2 and IL-12 and was endotoxin-independent. This is the first report of a pathogen protein that binds exclusively to NK cells and the first report of a nematode-derived product that induces abundant levels of cytokines from NK cells. Such an interaction could provide a means of cross-regulating deleterious Th2 immune responses in the host, thereby contributing to the long-term survival of N. americanus.
Hsieh
George C-F
GC
Department of Microbiology and Tropical Medicine, The George Washington University Medical Center, Washington, DC 20037, USA.
Loukas
Alex
A
Wahl
Allison M
AM
Bhatia
Monica
M
Wang
Yan
Y
Williamson
Angela L
AL
Kehn
Kylene W
KW
Maruyama
Haruhiko
H
Hotez
Peter J
PJ
Leitenberg
David
D
Bethony
Jeff
J
Constant
Stephanie L
SL
D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D004731:Endotoxins / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000276:immunology; D018664:Interleukin-12 / Q000276:immunology / Q000378:metabolism; D007376:Interleukin-2 / Q000276:immunology / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology* / Q000469:parasitology; D051379:Mice; D017221:Necator americanus / Q000276:immunology*; D011506:Proteins / Q000276:immunology / Q000378:metabolism
D000947:Antigens, Helminth; D004731:Endotoxins; D007376:Interleukin-2; D011506:Proteins; D018664:Interleukin-12; D007371:Interferon-gamma