About half of patients hospitalized with COVID-19 develop dangerous immune system proteins that attack the body’s own tissues, a new study finds.
Stanford University researchers studied blood samples from almost 200 patients hospitalized with Covid in the early months of the pandemic and identified signals in these patients’ blood that were similar to those in patients with lupus and other autoimmune conditions.
Half of the patients developed what are known as autoantibodies
About 20 percent of the patients whose blood was drawn multiple times had developed these ‘rogue antibodies’ within their first week at the hospital, the researchers found.
‘If you get sick enough from COVID-19 to end up in the hospital, you may not be out of the woods even after you recover,’ one of the study’s senior authors said.
Further study is needed to determine the links between these autoantibodies and severe Covid symptoms, as well as potential links with long Covid.
Over half of patients hospitalized with Covid develop ‘rogue antibodies’ that attack their own body tissue, a new study finds. Pictured: A healthcare worker treats a patient in the Covid ICU at Freeman Hospital West in Joplin, Missouri, August 2021
The Covid patients tested positive for a number of autoantibodies associated with different autoimmune conditions
From the beginning of the pandemic, doctors have noticed that patients with severe Covid cases share common symptoms with autoimmune diseases.
In autoimmune diseases, a person’s immune system mistakenly attacks other parts of the body instead of attacking a foreign virus or another type of invader.
These autoimmune conditions include lupus, celiac diseases and Type 1 diabetes.
Autoimmune conditions often involve swelling, blood clots, fatigue, and fever – all symptoms that doctors have observed in Covid patients.
Researchers have also suggested that an autoimmune reaction may be one driver of long Covid, in which patients suffer from symptoms for much longer than a typical two-week infection period.
A new study – published Tuesday in Nature Communications – reveals just how common autoimmune reactions may be in seriously ill Covid patients.
The study was led by researchers at Stanford University, Philipps University Marburg in Germany and the University of Pennsylvania.
The researchers studied blood samples from patients who were hospitalized with Covid in March and April 2020.
This included 147 patients at facilities affiliated with Stanford and 48 patients at Kaiser Permanente, another California hospital system.
In studying these blood samples, the researchers looked for autoantibodies, which are types of immune system protein that attacks the body’s own tissues, often driving autoimmune conditions.
Previous research has found autoantibodies in Covid patients and in children with Multisystem Inflammatory Syndrome in Children (MIS-C).
The Stanford researchers looked for many different antibodies, including those associated with different autoimmune diseases like lupus and systemic sclerosis.
Compared to healthy controls (HC), the Covid patients were more likely to test positive for autoantibodies that are common in connective tissue diseases and other conditions
Overall, they found that over half of the Covid patients had at least one type of autoantibody in their blood compared to less than 15 percent of healthy patients used as controls.
This autoimmune reaction may be caused by intense, long-term Covid infection sending the immune system into ‘overdrive,’ the researchers said in a press release.
For some patients, a coronavirus infection might trigger higher levels of natural immune system proteins that were present before the virus entered the body.
For others, the immune system may be triggered by coronavirus particles that look like human proteins.
‘It’s possible that, in the course of a poorly controlled SARS-CoV-2 infection – in which the virus hangs around for too long while an intensifying immune response continues to break viral particles into pieces – the immune system sees bits and pieces of the virus that it hadn’t previously seen,’ explained Dr PJ Utz, immunology professor at Stanford and senior author on the study.
‘If any of these viral pieces too closely resemble one of our own proteins, this could trigger autoantibody production.’
About 60 percent of the patients had anti-cytokine antibodies, which attack proteins involved in cell signaling and are common in autoimmune diseases.
One-fourth of the patients had anti-nuclear antibodies, another common autoantibody associated with these conditions.
And, in one specific blood test that looked for numerous different antibodies at once, 41 out of 51 (80 percent) patients tested positive for at least one autoantibody.
Some of the Covid patients tested positive for two or more autoantibodies
A small number of patients tested positive for two or more autoantibodies, and some even tested positive for these dangerous ‘rogue antibodies’ early in their hospital stays.
‘Within a week after checking in at the hospital, about 20 percent of these patients had developed new antibodies to their own tissues that weren’t there the day they were admitted,’ Utz said.
‘In many cases, these autoantibody levels were similar to what you’d see in a diagnosed autoimmune disease.’
These findings may suggest that seriously ill Covid patients could suffer from autoimmune-like conditions after recovering from their initial infection.
Or, as Utz put it: ‘If you get sick enough from COVID-19 to end up in the hospital, you may not be out of the woods even after you recover.’
The findings give Americans further motivation to get vaccinated, Utz said, because vaccination does not trigger the body’s autoimmune response in the same way that a Covid infection can.
‘If you haven’t been vaccinated and are telling yourself, ‘Most people who get COVID get over it and are OK,’ remember that you can’t know in advance that when you get COVID-19 it will be a mild case,’ Utz said.
‘If you do get a bad case, you could be setting yourself up for a lifetime of trouble because the virus may trip off autoimmunity.’
Utz and fellow scientists plan to continue investigating the links between autoimmunity and severe Covid disease, as well as the links between autoimmunity and long Covid.