Nanoparticles and the immune system

Abstract

Today nanotechnology is finding growing applications in industry, biology, and medicine. The clear benefits of using nanosized products in various biological and medical applications are often challenged by concerns about the lack of adequate data regarding their toxicity. One area of interest involves the interactions between nanoparticles and the components of the immune system. Nanoparticles can be engineered to either avoid immune system recognition or specifically inhibit or enhance the immune responses. We review herein reported observations on nanoparticle-mediated immunostimulation and immunosuppression, focusing on possible theories regarding how manipulation of particle physicochemical properties can influence their interaction with immune cells to attain desirable immunomodulation and avoid undesirable immunotoxicity.

Figure 1

Nanoparticle interactions with the immune system. Nanoparticles’ effects on the immune cells may benefit treatment of disorders mediated by unwanted immune responses and enhance immune response to weak antigens. On the other hand, undesirable immunostimulation or immunosuppression by nanoparticles may result in safety concerns and should be minimized.

Figure 2

Hypothetical model of nanoparticle antigenicity. Nanoparticles (dendrimers and fullerenes) may not be antigenic unless they are bound to a protein carrier such as BSA. BSA-nanoparticle conjugate is endocytosed by B cells, and the protein is digested inside the cell. B cells then may present BSA peptides on their human leukocyte antigen-class II molecules to T-helper cells. Both cells become activated, resulting in production of cytokines by T lymphocytes and antibodies directed to nanoparticles by plasma B cells. The protein carrier is indispensable for T cell activation. Antibodies to fullerenes and dendrimers are produced by different B cells. For simplicity of the figure, only one B cell is shown. TCR, T cell receptor.