Activation of natural killer cells during acute infection with hepatitis C virus.
OBJECTIVE
Natural killer (NK) cells are essential early after infection, not only for viral containment but also for timely and efficient induction of adaptive responses. An inhibitory effect of hepatitis C virus (HCV)-E2 proteins on NK cells has been reported, but the features of NK cell responses in the acute phase of hepatitis C are still largely undefined. Therefore, the aim of this study was to characterize the function and phenotype of NK cells in the acute phase of infection and compare individuals with chronic and self-limited outcomes.


METHODS
Twenty-two individuals with acute HCV infection, 14 with chronic evolution, and 8 with self-limited infection, were studied using NK phenotypic and functional assays.


RESULTS
An increased expression of NKG2D on both CD56(bright) and CD56(dim) NK cells was detected in patients with acute HCV, irrespective of the outcome, as compared with healthy controls. Also, interferon gamma production and cytotoxicity by NK cells were higher in individuals with acute HCV infection than in healthy controls. Subset analysis showed increased interferon gamma production in both NK cell subsets carrying group 1 and group 2 HLA-C-specific killer cell immunoglobulin-like receptors. However, increased CD107a was noted only on NK cells expressing the group 1 HLA-C-specific killer cell immunoglobulin-like receptor and was maximal in self-limited infection.


CONCLUSIONS
Our data show that in the acute phase of HCV infection, NK cells are activated regardless of outcome, with no evidence of a suppressive effect of HCV on NK cell function.
Amadei
Barbara
B
Laboratory of Viral Immunopathology, Unit of Infectious Diseases and Hepatology, Azienda Ospedaliera-Universitaria di Parma, Parma, Italy.
Urbani
Simona
S
Cazaly
Angelica
A
Fisicaro
Paola
P
Zerbini
Alessandro
A
Ahmed
Parvin
P
Missale
Gabriele
G
Ferrari
Carlo
C
Khakoo
Salim I
SI
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D019002:CD56 Antigen / Q000032:analysis; D003602:Cytotoxicity, Immunologic; D005260:Female; D006526:Hepatitis C / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008875:Middle Aged; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000032:analysis; D054340:Receptors, KIR / Q000032:analysis
D019002:CD56 Antigen; C527085:KLRK1 protein, human; D055655:NK Cell Lectin-Like Receptor Subfamily K; D054340:Receptors, KIR; D007371:Interferon-gamma