n their latest study, Iwasaki’s team analyzed blood samples from patients in the Mount Sinai-Yale Long COVID study. This cohort of over 215 Long COVID patients is part of a collaboration between Iwasaki and David Putrino, PhD, professor in the Department of Rehabilitation and Human Performance at Icahn School of Medicine at Mount Sinai in New York City. As part of this joint effort, Putrino’s clinic obtained blood samples from patients enrolled in the study. Iwasaki’s laboratory then purified antibodies from the blood and transferred them into healthy mice.

Next, the researchers led by Keyla Sá, a postdoctoral fellow in Iwasaki’s lab, conducted multiple behavioral experiments to look for Long COVID symptoms. While many of these experiments found no significant difference between the experimental and control mice, a few revealed striking changes in those that received antibodies.

In one such experiment, researchers placed the mice on a heated plate and measured how long it took for them to react. Some mice that received antibodies reacted significantly more quickly to the heat, indicating a heightened sensitivity to pain. The researchers went back and identified the patients whose antibodies had been injected into the mice. Interestingly, these patients reported pain as one of their Long COVID symptoms.

Another experiment was the rotarod test, in which researchers placed mice on a rotating cylinder to measure coordination and balance. Mice that received antibodies were more likely to struggle to stay on the apparatus. Once again, when the researchers looked at the source of these antibodies, they learned that they were mostly from patients who reported suffering from dizziness.

The mice also underwent a grip strength test, in which researchers measured the force applied by the animals to a grid apparatus. A group of mice were found to have reduced muscle strength if they received antibodies from patients reporting tinnitus and headache. Thus, antibodies capable of impairing muscle function are found in patients with these symptoms. How exactly these antibodies cause pathology needs more study.