Natural killer cells and their function in Takayasu's arteritis.

Objective: Takayasu's arteritis (TAK) is a chronic, large vessel systemic vasculitis. Immune inflammatory response plays a crucial role in the pathogenesis of TAK. Natural killer (NK) cells are one of the major immunoregulatory cell groups of the immune system, but their role in TAK pathogenesis is unclear. We aimed to investigate the role of peripheral blood NK cells in TAK pathogenesis.

Methods: The study consisted of 47 TAK patients and 27 healthy controls. Peripheral blood natural killer (NK) cells and their CD56Dim/CD56Bright subsets were phenotyped using CD3 and CD56 surface markers. Functional potential was assessed by production of granzyme B, perforin and interferon (IFN)-γ.

Results: TAK patients had decreased numbers of NK cells in the peripheral blood (p<0.001) relative to healthy controls. The percentages of CD56Bright (p<0.05) and CD56Dim NK cells (p<0.001) from TAK patients were also decreased. The expressions of Granzyme B (p<0.001), Perforin (p<0.001) in NK cells were lower in TAK patients to compared control group, but no differences in the percentage of IFN-γ producing cells was observed between TAK patients and healthy control. There is no difference in the percentage of NK cells or CD56Bright or CD56Dim NK cells between active and inactive TAK. However, granzyme B-expressing NK cell percentage was significantly decreased in active TAK compared to inactive TAK (p<0.05).

Conclusions: Our findings concluded that NK cell numbers and cytotoxicity are reduced in TAK patients.