Microplastics that accumulate in the body may ‘clog up’ immune cells
Microplastics that accumulate in the body can disrupt the immune system by preventing immune cells from engulfing microbes and eliminating dead cells, according to a new study in mice and laboratory dishes. Although it is not yet clear how this might occur in the human body, experts say the study has potential implications for human health.
Microplastics are tiny particles that shed from plastic products, such as water bottles, food storage containers and freezer bags. Although these indigestible particles accumulate in the bodyscientists still don’t know exactly how they contribute to disease. The new study found that these tiny particles can clog and disrupt the functioning of macrophages, cells that engulf and destroy potentially harmful viruses, bacteria or fungi, as well as dead cells.
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The accumulation of microplastics in the body has been correlated with atherosclerosisin which plaque builds up in the inner walls of the arteries, making them narrow and stiff; neurodegeneration; And cancersaid Justin Perryimmunologist at Memorial Sloan Kettering Cancer Center and lead author of the study, published March 10 in the journal Immunity.
However, researchers have not proven that microplastics directly cause disease. “I think that really pushed me and other colleagues in the field to try to understand this,” Perry told Live Science. For the new study, he and his colleagues focused on polystyrenea common plastic used in food containers that breaks down into microplastic particles that can be as small as a virus or as large as a grain of sand.
The team focused on macrophageswhich engulf materials from their environment, such as dead cells and infectious microbes, and break them down into sugars, amino acids and fats that cells can recycle. Scientists have shown in mice and humans that Macrophages actively absorb microplastics but cannot break them down.
“It’s a little scary, because it means we haven’t really responded to these microplastics,” Perry said. It is therefore possible that cells accumulate increasing volumes of microplastics throughout a person’s life, he added.
Currently, there is no clear public health evidence directly linking exposure to microplastics to an increase in infections in humans.
Eliseo Castillo, microplastics researcher at the University of Mexico
Perry and his colleagues administered this non-biodegradable plastic to human macrophages grown in laboratory plates. They also inserted the microplastic particles into the mice’s airways, euthanized them, and extracted their lungs for viewing under a microscope. Cells that absorbed the particles had difficulty engulfing and destroying dead cells or infectious microbes like bacteria or fungi, the team found.
To determine whether microplastics could prevent macrophages from fighting infections, the team administered the fungus Aspergillus fumigatuswhat causes respiratory infections in immunocompromised people, to the lungs of mice. They found that mice given microplastics had difficulty clearing the infection and suffered even more severe illness.
“It’s still unclear whether this will lead to higher infection rates in humans,” Castillo said. “At present, there is no clear public health evidence directly linking exposure to microplastics to an increase in infections in humans.”
The microplastics also prevented macrophages from engulfing and destroying dead cells, potentially causing a buildup of waste in the tissues. Perry said people lose 2% of their body mass per day due to cell death, and it’s up to macrophages to remove the dead waste. “It’s about 3 million [dying] cells per second. If you really do the math, it’s a pretty heavy burden [for macrophages]”Perry added
A clump of dead cells like DNA can alert the immune system because it signals that a threat such as infection may cause tissue damage. This could trigger inflammation, potentially precipitating autoimmune diseases, Castillo said.
Microplastics may also reduce fertility when absorbed by macrophages in the testicles. Perry and colleagues exposed male mice to regular doses of microplastics and found that their sperm counts declined within 18 weeks. He assumed that microplastics can partly explain the decreased sperm count seen globally in the human population. The study did not explore the potential impact of these particles on female fertility.
Although researchers have demonstrated that human macrophages gobble up microplastics when grown in lab dishes, they still don’t know how easily the cells would do so in the body.
Perry plans to study samples taken from humans, particularly how microplastics might contribute to the formation of atherosclerotic plaques that clog blood vessels. We already know that macrophages loaded with undigested material accumulate in these plaques which stop blood circulationThat’s why he and his colleagues hypothesize that microplastics could make the problem worse, he said.
This article is for informational purposes only and is not intended to offer medical advice.
Codo, AC, Romero-Pichardo, JE, Wang, Z., Aufiero, MA, Lazarov, T., Saitz Rojas, W., Walker, NS, Nair, A., Cole, RF, Adkins, S., Dong, E., Fadojutimi, K., Martínez de la Torre, C., David, Y., Hohl, TM, Geissmann, F., Keshari, KR, Lucas, CD and Perry, JSA (2026). The pathophysiology induced by polystyrene microplastics is driven by the disruption of efferocytosis. Immunity, 59(3). https://doi.org/10.1016/j.immuni.2026.01.009
