From Nancy Lapid

May 28 (Reuters) - The results of two studies suggest that the debilitating neurological symptoms associated with long COVID are often caused by the body's immune system mistakenly attacking itself, which could pave the way for developing effective treatments for the condition and changing blood donation policies.

In both studies, researchers collected what are known as autoantibodies from the blood of volunteers with long COVID or post-COVID-19.

Normally, antibodies in the immune system defend the body against attacks, but autoantibodies, which often appear after acute viral infection and persist with long COVID, mistakenly attack the body.

When healthy mice are injected with these human autoantibodies, they exhibit neurological symptoms that mimic those experienced by patients, including fatigue, loss of balance, increased sensitivity to pain, and nerve fiber damage.

A research paper published in the journal Cell Reports Medicine stated that in one experiment, this effect was repeated even when autoantibodies were collected from patients two years after the initial infection.

"This new understanding of the nature of long COVID will enable us to develop a number of effective treatments for autoimmune diseases that could greatly improve the symptoms of millions of people with this chronic condition," said Dr. David Buterino of the Icahn School of Medicine at Mount Sinai in New York, one of the authors of a separate study published in the journal Cell.

He added, "Previously we had no way of predicting who would benefit from (current) treatments... Our study now shows that if you are in a category of long-term COVID patients who have autoantibodies in their bodies... you may be a good candidate for these drugs."

A commentary published in the newspaper stated that the two studies "provide strong evidence that autoantibodies directly contribute to the onset of symptoms in a subset of those with long COVID," but neither provides conclusive evidence of a single central mechanism underlying this condition.

Besides the clinical significance of the findings, Potreno believes they carry an urgent public health warning regarding blood donation.

He noted that "in Britain, having long COVID is a reason to avoid donating blood, while in the United States these people are still allowed to donate."

He added, "Given the risks that (autoantibodies in) the plasma of people with long COVID may pose to others, this country should consider making fundamental changes to its (blood) donation policies."