Binding of Soluble Yeast β-Glucan to Human Neutrophils and Monocytes is Complement-Dependent

The immunomodulatory properties of yeast β-1,3/1,6 glucans are mediated through their ability to be recognized by human innate immune cells. While several studies have investigated binding of opsonized and unopsonized particulate β-glucans to human immune cells mainly via complement receptor 3 (CR3) or Dectin-1, few have focused on understanding the binding characteristics of soluble β-glucans. Using a well-characterized, pharmaceutical grade, soluble yeast β-glucan, this study evaluated and characterized the binding of soluble β-glucan to human neutrophils and monocytes. The results demonstrated that soluble β-glucan bound to both human neutrophils and monocytes in a concentration-dependent and receptor-specific manner. Antibodies blocking the CD11b and CD18 chains of CR3 significantly inhibited binding to both cell types, establishing CR3 as the key receptor recognizing the soluble β-glucan in these cells. Binding of soluble β-glucan to human neutrophils and monocytes required serum and was also dependent on incubation time and temperature, strongly suggesting that binding was complement-mediated. Indeed, binding was reduced in heat-inactivated serum, or in serum treated with methylamine or in serum reacted with the C3-specific inhibitor compstatin. Opsonization of soluble β-glucan was demonstrated by detection of iC3b, the complement opsonin on β-glucan-bound cells, as well as by the direct binding of iC3b to β-glucan in the absence of cells. Binding of β-glucan to cells was partially inhibited by blockade of the alternative pathway of complement, suggesting that the C3 activation amplification step mediated by this pathway also contributed to binding

On the trade-off between privacy and utility in mobile services: a qualitative study

While the widespread use of mobile services offers a variety of benefits to mobile users, it also raises serious privacy concerns. We report the results of a user study that investigated the factors that influence the decision-making process pertaining to the trade-off between privacy and utility in mobile services. Through two focus groups, 16 individual interviews and a questionnaire survey involving 60 participants, the study identified awareness and knowledge of privacy risks, trust in service providers, desire for mobile services, and belief of cyber privacy as four factors that contribute to the perceived trade-off. The results also suggest that, with appropriate adoption, privacy-preserving tools can positively influence the privacy trade-off. In addition, our findings explore the cultural differences regarding privacy between participants from western countries (with the UK as the main representative) and China. In particular, the results suggest that participants from China are more likely to be comfortable with a government department protecting their individual privacy, while participants from western countries are more likely to wish to see such responsibility reside with some combination of individuals and non-governmental organisations