Nanoplastics is a new type of environmental pollutant. Its particles can easily enter the bodies of animals through diet and breathing, and affect the physiological functions of organisms.

Though vulnerable to nanoplastics, immune cells are an important line of defense against foreign antigens. However, little is known about the toxic effects of nanoplastics on immune systems of mammals. 

Recently, a research team led by Prof. Xu Mingkai from the Institute of Applied Ecology (IAE) of the Chinese Academy of Sciences examined toxic effects and underlying mechanisms of polystyrene nanoplastics (PS-NPs) on immune cells. 

The researchers found that PS-NPs of different surface charges and varying particle sizes could all enter splenic lymphocytes of the mouse, decrease cell viability at high concentrations, and induce cell apoptosis.

However, positive, negative and uncharged nanoplastics exerted the toxicity in different ways and extents, while nanoplastics of certain sizes could penetrate into cells more efficiently.  

They found that PS-NPs inhibited a number of key signaling pathways that are responsible for the activation and differentiation of T lymphocytes (e.g., CD8⁺ T cells), thereby affecting their immune function.

These findings would be beneficial for predicting the ecological risk of nanoplastic pollution. 

The study, published in Journal of Hazardous Materials, was supported by the National Natural Science Foundation of China, the Liaoning Revitalization Talents Program, and the Young and Middle-aged S&T Innovative Talents Program of Shenyang Science and Technology Bureau.