Objective      To analyze the distribution and phenotype of neutrophils in periphery blood and different types of gastric tissues from gastric cancer (GC) patients

and to investigate the influence of GC tissue culture supernatants induced-conditioned neutrophils (GCSI-CNs) on CD3

+

T cells.        Methods      Flow cytometry was employed to detect and analyze the ratio and phenotype of CD66b

+

neutrophils in tumoral

peritumoral and norma

l gastric tissues and peripheral blood of 42 GC patients. Then

paraffin-embedded tissues of GC patients were investigated immunohistochemically with anti-human CD15 antibody to analyze the infiltration of neutrophils

in situ

. Finally

GCSI-CNs were cocultured with CD3

+

T cells

and the proliferation of CD3

+

T cells was analyzed by flow cytometry.        Results      The percentage of neutrophils in periphery blood of GC patients was much higher than that in healthy donors (

P

<

0.01). The frequency of neutrophils was significantly higher in tumoral gastric tissues than in peritumoral (

P

<

0.05) or in normal gastric tissues (

P

<

0.05). Meanwhile

neutrophils infiltrated in different types of gastric tissues and in periphery blood of GC patients were probably mainly mature segmented neutrophils. In addition

GCSI-CNs significantly inhibited the proliferation of CD3

+

T cells.       Conclusion      Neutrophils are accumulated in GC microenvironment and may facilitate the progression of GC by inhibiting the proliferation of CD3

+

T cells.