Nikhil Prasad Fact checked by:Thailand Medical News Team Feb 14, 2026 2 hours, 17 minutes ago
Medical News: A new study by scientists from the National Institute for Infectious Diseases Lazzaro Spallanzani IRCCS, the San Camillo Forlanini Hospital, ETH Zürich, ASL Roma 1 and the San Giovanni Battista Hospital suggests that hidden autoimmune reactions may be driving persistent fatigue and other symptoms in Long COVID patients.
Hidden immune antibodies may be fueling persistent fatigue and brain fog in Long COVID patients.
A Search for Biological Markers
Long COVID continues to puzzle doctors worldwide. Many sufferers experience months of exhaustion, brain fog, palpitations, breathlessness and poor exercise tolerance, yet routine medical tests often appear normal. In this
Medical News report, researchers focused on a specific group of immune proteins called autoantibodies that mistakenly attack the body’s own receptors.
The team studied 15 individuals previously infected with SARS-CoV-2. Eleven had severe Long COVID, defined as having more than four persistent symptoms lasting over three months. Four others had recovered fully and served as comparison controls.
Autoantibodies Target Key Body Systems
The researchers measured autoantibodies directed at G-protein-coupled receptors, or GPCRs. These receptors play critical roles in regulating heart rate, blood pressure, blood vessel tone, nervous system signaling and immune balance.
Long COVID patients showed higher average levels of these autoantibodies compared to recovered individuals. Particularly striking were antibodies targeting the beta-2 adrenergic receptor, a receptor deeply involved in immune control and blood vessel function. Although the small sample size prevented statistical certainty, the trend was consistent across nearly all receptor types tested.
The data also revealed that these autoantibodies did not act alone. They clustered together, forming what researchers described as a coherent autoimmune signature. Patients with higher antibody levels tended to report more severe fatigue, worse cognitive problems, orthostatic intolerance and reduced exercise capacity.
Hormones and Immune Weakness
Another important finding involved cortisol, a hormone produced by the adrenal glands that helps regulate stress and inflammation. Morning cortisol levels were significantly lower in Long COVID patients compared to those who had recovered without symptoms. Lower cortisol may weaken the body’s ability to control inflammation.
In addition, Long COVID patients showed weaker T-cell responses to SARS-CoV-2 proteins, particularly the Spike protein. This suggests a reduced antiviral immune response, potentially allowing lingering viral fragments to continue stimulating the immune system.
Diagnostic and Treatment Implications
Using calculated cut-off values, researchers were able to identify 5 out of 11 Long COVID patients based solely on elevated GPCR autoantibodies, without producing false positives in controls. While preliminary
, this approach hints at the possibility of future blood tests that could help confirm Long COVID in selected patients.
The findings also raise interest in immunomodulatory treatments such as intravenous immunoglobulin or immunoadsorption, which aim to remove harmful antibodies from circulation. However, larger controlled studies are needed before any firm treatment recommendations can be made.
A Step Toward Understanding
Although the study involved only a small group and cannot prove direct causation, it strengthens the theory that immune-driven receptor dysfunction may underlie many Long COVID symptoms. The clustering of antibodies alongside fatigue severity suggests that the immune system’s misdirected response could be central to the condition rather than incidental.
The researchers caution that larger, long-term investigations are essential to confirm these results and determine whether antibody-targeted therapies truly improve outcomes. Nevertheless, these findings represent an important step toward identifying measurable biological markers for a condition that has often been dismissed as subjective.
The study findings were published in the peer reviewed: International Journal of Molecular Sciences.
https://www.mdpi.com/1422-0067/27/4/1787
For the latest on Long COVID, keep on logging to Thailand
Medical News.
Read Also:
https://www.thailandmedical.news/articles/long-covid
https://www.thailandmedical.news/articles/coronavirus
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