Phenotypic study of natural killer cell subsets in ankylosing spondylitis patients.

It has been demonstrated that natural killer (NK) cells play a role in regulation of autoimmunity. They play a protective role in several rodent disease models. In this study we aimed to compare the immunophenotypic features of NK cells in Ankylosing Spondylitis (AS) with normal subjects with regard to CD56 and CD16 molecules. This study was carried out on 30 AS patients and 33 normal volunteer donors. Peripheral Blood Mononuclear cells (PBMC) were tested by flow cytometry detecting the intensity of CD56 and CD16 surface molecules. The percentage of positive cells and their subsets were then calculated and statistically analyzed using SPSS software. A significant increase was found in CD56+ CD16+ (P < or = 0.009), and also in the subset of CD56 dim CD16+ (P < or = 0.02), but not in CD56 bright CD16+ (P=0.3) NK cells in AS patients compared to controls. We conclude that these results may indicate that NK and their subset ratios play a role in AS pathogenesis. Moreover, determination of NK subsets in combination with clinical features may be useful for AS diagnosis. However, further studies using large samples together with determination of relevant cytokines are recommended to verify the exact role of NK in AS disease.