Background: Natural killer (NK)-like T cells comprising CD56(+) T cells and CD57(+) T cells belong to a subset of CD1d-independent NKT cells playing an important role in regulating immune responses. Although NK-like T cells are reported to increase in patients with advanced gastric carcinomas, it remains unknown how NK-like T cells are involved in disease progression in gastric cancer patients.
Methods: The proportions of Th1 cells (interferon [IFN]-gamma-producing CD4(+) T cells), Th2 cells (IL-4-producing CD4(+) T cells), and NK-like T cells (CD56(+) T cells and CD57(+) T cells) in the peripheral blood of 48 gastric cancer patients and 20 healthy controls were measured by two-color flow cytometry analysis and by intracellular cytokine analysis to investigate an association of these immune cells with the survival rate of gastric cancer patients.
Results: Univariate analysis showed that Th1 cells and CD57(+) T cells, as well as some clinicopathological factors, significantly influenced the survival rate. CD57-high (> or ==18%) patients survived for a significantly shorter period after surgery compared to CD57-low patients (P = 0.046; Kaplan-Meier, log-rank test) in the stage III-IV patients, but not in the stage I-II patients. Further, multivariate analysis showed that lymphatic invasion was a statistically significant independent risk factor in all the gastric cancer patients, but the proportion of CD57(+) T cells as well as depth of tumor were statistically significant independent risk factors in patients with advanced carcinomas (stage III-IV).
Conclusion: An increased proportion (> or ==18%) of CD57(+) T cells in the peripheral blood of patients with advanced gastric carcinomas could indicate a poor prognosis.