Impact of nanoparticles on the immune system.

Nanotechnology is a fast growing field and its increasing exposure to humans and environment has generated the need to study the impact of nano-materials on host's immune system. Though, the effect of different particles on the various physiological functions will largely depend on their chemical composition and expectations of fundamentally large deviations in the particle activity or their mode of action at nano scale size should not be over stretched. Nonetheless, owing to their small size, nanoparticles can penetrate and accumulate much deeper breaching the cellular and even sub-cellular boundaries which can cause many undesirable and un-characterized effects. Nanoparticles may escape the phagocytic activity of macrophages, bind to serum proteins and act as haptens; activate complement cascades; disturb the Th1/Th2 balance; cause hemolysis or thrombogenecity and may perturb the adaptive or innate immunity leading to a hyper-activated immune state or even a suppressed immunophenotype. Since none of the cellular or even subcellular barriers are impervious to nanoparticles, our earlier studies thoroughly characterizing the activity of diverse compounds or formulations at macro size level may not hold relevance at nano-dimensions. Moreover, our understanding of the properties of matter when it squeezes to nano dimensions is still in very preliminary phase, therefore it becomes extremely critical to thoroughly evaluate the nanoparticles before adopting them for widespread usage in environment and direct or indirect human exposure.