No abstract

NK cells play an important role in innate immunity. A previous genome-wide association study demonstrated an association between a 17q12 allele (rs9916629C) and lower frequency of CD3−CD56+ NK cells in peripheral blood. We performed an analysis that not only replicates the original result of the genome-wide association study (p = 0.036) but also defines the specific cell subpopulations and functions that are modulated by the rs9916629 polymorphism in a cohort of 96 healthy adult subjects using targeted multiparameter flow cytometric profiling of NK cell phenotypes and functions. We found that rs9916629C is associated with alterations in specific NK cell subsets, including lower frequency of predominantly cytotoxic CD56dim NK cells (p = 0.011), higher frequency of predominantly regulatory CD56bright NK cells (p = 0.019), and a higher proportion of NK cells expressing the inhibitory NKG2A receptor (p = 0.0002). Functionally, rs9916629C is associated with decreased secretion of macrophage inflammatory protein-1β by NK cells in the context of Ab-dependent cell-mediated cytotoxicity (p = 0.039) and increased degranulation in response to MHC class I-deficient B cells (p = 0.017). Transcriptional profiling of NK cells suggests that rs9916629 influences the expression of transcription factors such as TBX21, which has a role in NK cell differentiation, offering a possible mechanism for the phenotypic and functional differences between the different alleles. The rs9916629C allele therefore has a validated effect on the proportion of NK cells in peripheral blood and skews NK cells toward a specific phenotypic and functional profile, potentially influencing the impact that these innate immune cells have on infection and autoimmunity.

Cross-linking reaction with transglutaminase (m-TG) was used to obtain yoghurt produced with YO-MIX TM 511 yoghurt starter (Danisco). The use of two different temperatures (37 and 42°C), the presence of m-TG and the storage time (28 days) of the yoghurt were the factors that influenced the immunoreactive and sensory properties. The ELISA results obtained during the reaction of yoghurt proteins with a specific antibody against individual milk proteins (b-lactoglobulin, a-lactalbumin, a-casein, b-casein and j-casein) indicated differences on the level of immunoreactivity of individual proteins. The b-lg immunoreactivity of yoghurt produced at 37°C was not detectable in any of the samples whereas during the process conducted at 42°C the presence of this protein at low level was observed (1.00 and 3.33% without and with m-TG, respectively). The lack of j-casein was detected in the storage yogurt sample prepared during fermentation at 42°C. The samples were subjected to sensory evaluation using quantitative descriptive analysis (QDA). A trained personnel (n = 6) rated the yogurts for smell, taste and texture. The data obtained from QDA (16 attributes and 4 yoghurts) were subjected to a principal component analysis (PCA). The results (QDA and PCA) proved that the addition of the m-TG enzyme had significant impact on the sensory quality of the samples. Four principal components (PC1-PC4) determined 96.05% of the total variance of the samples.