The crystal structure of titanium dioxide nanoparticles influences immune activity in vitro and in vivo.

Our data show that measuring CD83 and CD86 expression and IL-12p40 and TNF-α production in DC in vitro may provide an efficient way to screen NP for potential adjuvant activity; future studies should establish whether this also holds for other NP. Based on antigen-specific IgE and IgG1, anatase NP have higher adjuvant activity than rutile NP, confirming our in vitro data. Other parameters of the allergic response showed a similar response for the two NP crystal structures. From the viewpoint of safe(r) by design products, rutile NP may be preferred over anatase NP, especially when inhalation exposure can be expected during production or application of the product.