Immune Toxicity of and Allergic Responses to Nanomaterials

Over the past decade, the remarkable development of nanomaterials and nanotechnology has led to their use in many applications. But as the uses of nanomaterials have increased, so have concerns regarding their potential adverse effects (that is, nanotoxicity) in humans and the environment. Because the body’s immune systems are responsible for dealing with foreign substances, we likely should expect at least some interaction of nanomaterials with our immune systems with daily use of nanomaterials, and we must understand those interactions in order to use nanomaterials safely or to develop safer nanomaterials. In this review, we summarize recent advances in immunotoxicology studies of nanomaterials, especially (1) macrophage recognition of nanomaterials with particular emphasis on the effect of particle size, and (2) in vivo responses after skin exposure to nanomaterials, including the onset or aggravation of allergy. In addition, we discuss challenges to further understanding the immune system–nanomaterial interaction, with the goal of increasing the safety of these compounds.