Dr. Jeroen den Dunnen
@drdendunnen.bsky.social
Immunologist and Head of Department of CIMM at the Amsterdam UMC, Netherlands. My team studies the role of antibodies during infection and autoimmune diseases, with a particular focus on post-acute infection syndromes (PAIS), such as Long-COVID and ME/CFS.
Taken together, both “ends” of the antibody response appear affected in Long COVID:
– the antigen binding part (Fab)
– the tail (Fc)
This may not only impede SARS-CoV-2 clearance, but also hint at broader immune dysfunction.
– the antigen binding part (Fab)
– the tail (Fc)
This may not only impede SARS-CoV-2 clearance, but also hint at broader immune dysfunction.
August 30, 2025 at 8:06 PM
Taken together, both “ends” of the antibody response appear affected in Long COVID:
– the antigen binding part (Fab)
– the tail (Fc)
This may not only impede SARS-CoV-2 clearance, but also hint at broader immune dysfunction.
– the antigen binding part (Fab)
– the tail (Fc)
This may not only impede SARS-CoV-2 clearance, but also hint at broader immune dysfunction.
🔹 Aberration 2: Impaired class switching.
Normally, B cells switch from IgM to potent, long-lasting IgG.
In Long COVID, this switch is blunted — reducing the production of high-affinity IgG needed for viral clearance.
Normally, B cells switch from IgM to potent, long-lasting IgG.
In Long COVID, this switch is blunted — reducing the production of high-affinity IgG needed for viral clearance.
August 30, 2025 at 8:06 PM
🔹 Aberration 2: Impaired class switching.
Normally, B cells switch from IgM to potent, long-lasting IgG.
In Long COVID, this switch is blunted — reducing the production of high-affinity IgG needed for viral clearance.
Normally, B cells switch from IgM to potent, long-lasting IgG.
In Long COVID, this switch is blunted — reducing the production of high-affinity IgG needed for viral clearance.
🔹 Aberration 1: Immunological imprinting (“original antigenic sin”).
Instead of mounting fresh responses to SARS-CoV-2, B cells fall back on memory from seasonal coronaviruses. The result: antibodies less effective against the new virus.
Instead of mounting fresh responses to SARS-CoV-2, B cells fall back on memory from seasonal coronaviruses. The result: antibodies less effective against the new virus.
August 30, 2025 at 8:06 PM
🔹 Aberration 1: Immunological imprinting (“original antigenic sin”).
Instead of mounting fresh responses to SARS-CoV-2, B cells fall back on memory from seasonal coronaviruses. The result: antibodies less effective against the new virus.
Instead of mounting fresh responses to SARS-CoV-2, B cells fall back on memory from seasonal coronaviruses. The result: antibodies less effective against the new virus.
The results:
– Reduced SARS-CoV-2 spike-specific IgG and IgA
– Elevated IgG against spike of seasonal coronaviruses
This points to two distinct immunological abnormalities 👇
– Reduced SARS-CoV-2 spike-specific IgG and IgA
– Elevated IgG against spike of seasonal coronaviruses
This points to two distinct immunological abnormalities 👇
August 30, 2025 at 8:06 PM
The results:
– Reduced SARS-CoV-2 spike-specific IgG and IgA
– Elevated IgG against spike of seasonal coronaviruses
This points to two distinct immunological abnormalities 👇
– Reduced SARS-CoV-2 spike-specific IgG and IgA
– Elevated IgG against spike of seasonal coronaviruses
This points to two distinct immunological abnormalities 👇
Aberrant immune responses have long been suspected to play a role in #LongCOVID.
Here, we examined antibody profiles against both SARS-CoV-2 and the “everyday” seasonal coronaviruses. 2/6
Here, we examined antibody profiles against both SARS-CoV-2 and the “everyday” seasonal coronaviruses. 2/6
August 30, 2025 at 8:06 PM
Aberrant immune responses have long been suspected to play a role in #LongCOVID.
Here, we examined antibody profiles against both SARS-CoV-2 and the “everyday” seasonal coronaviruses. 2/6
Here, we examined antibody profiles against both SARS-CoV-2 and the “everyday” seasonal coronaviruses. 2/6
Also pretty proud of my team Oliver Chen, Amélie Bos, and Ashwin Mak (2 oral presentations, 3 posters) that resp. showed that Long COVID autoantibodies remain pathogenic for years, can directly affect skeletal muscle cells, and that patients show impaired antibody isotype switching. 7/
August 13, 2025 at 4:16 PM
Also pretty proud of my team Oliver Chen, Amélie Bos, and Ashwin Mak (2 oral presentations, 3 posters) that resp. showed that Long COVID autoantibodies remain pathogenic for years, can directly affect skeletal muscle cells, and that patients show impaired antibody isotype switching. 7/
@virusesimmunity.bsky.social showed that IgG of Long COVID patients that is transferred to mice partially ends up in the brain, indicating that these IgGs may disrupt the blood-brain barrier. Could be an important step in the development of neurological symptoms. 6/
August 13, 2025 at 4:16 PM
@virusesimmunity.bsky.social showed that IgG of Long COVID patients that is transferred to mice partially ends up in the brain, indicating that these IgGs may disrupt the blood-brain barrier. Could be an important step in the development of neurological symptoms. 6/
Maureen Hansen presented her recently published work on identification of circulating cell-free RNA signatures for the characterization and diagnosis of ME/CFS: www.pnas.org/doi/10.1073/... 5/
Circulating cell-free RNA signatures for the characterization and diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome | PNAS
People living with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) experience
heterogeneous and debilitating symptoms that lack suffici...
www.pnas.org
August 13, 2025 at 4:16 PM
Maureen Hansen presented her recently published work on identification of circulating cell-free RNA signatures for the characterization and diagnosis of ME/CFS: www.pnas.org/doi/10.1073/... 5/
Esther Melamed showed that 25% of the patients in their (large) cohort display anti-ganglioside antibodies (not included in most autoantibody arrays): www.medrxiv.org/content/10.1... Let’s all check this in our cohorts! 4/
Analysis of 977 Long COVID Patients Reveals Prevalent Neuropathy and Association with Anti-Ganglioside Antibodies
Background Long COVID (LC) is a novel condition that is characterized by persistent symptoms that last from months to years following a SARS-CoV-2 infection. While LC symptoms vary widely, neuropathy ...
www.medrxiv.org
August 13, 2025 at 4:16 PM
Esther Melamed showed that 25% of the patients in their (large) cohort display anti-ganglioside antibodies (not included in most autoantibody arrays): www.medrxiv.org/content/10.1... Let’s all check this in our cohorts! 4/
In vivo models: more and more mouse models are being developed to study pathophysiology and therapies. Nadia Roan showed that machine learning is a promising strategy to boost the quality of Long COVID models, and (successfully) test therapies. 3/
August 13, 2025 at 4:16 PM
In vivo models: more and more mouse models are being developed to study pathophysiology and therapies. Nadia Roan showed that machine learning is a promising strategy to boost the quality of Long COVID models, and (successfully) test therapies. 3/
First, a call to action from @virusesimmunity.bsky.social to combine all our data internationally. Maureen Hansen mentioned that such a repository website already exists for #MECFS MAPMECFS.org. Could we make this for Long COVID as well? 2/
Welcome - mapMECFS
MAPMECFS.org
August 13, 2025 at 4:16 PM
First, a call to action from @virusesimmunity.bsky.social to combine all our data internationally. Maureen Hansen mentioned that such a repository website already exists for #MECFS MAPMECFS.org. Could we make this for Long COVID as well? 2/
Finally, big thanks to the involved doctors Thadé Goderie, Niek Versfeld, and Alain Bauwens. And to Noaharu Kitajima, who previously described post-acute infection dizziness like this after influenza: pubmed.ncbi.nlm.nih.gov/27089972/ 10/10
pubmed.ncbi.nlm.nih.gov
June 25, 2025 at 9:37 AM
Finally, big thanks to the involved doctors Thadé Goderie, Niek Versfeld, and Alain Bauwens. And to Noaharu Kitajima, who previously described post-acute infection dizziness like this after influenza: pubmed.ncbi.nlm.nih.gov/27089972/ 10/10
So if dizziness is your ONLY post-COVID symptom, you could ask your GP to check your eardrum during nasal respiration. If it moves, placing a ventilation tube may work. If afterwards your eye muscles become painful, vestibulo-visual rehabilitation may work. 9/10
June 25, 2025 at 9:37 AM
So if dizziness is your ONLY post-COVID symptom, you could ask your GP to check your eardrum during nasal respiration. If it moves, placing a ventilation tube may work. If afterwards your eye muscles become painful, vestibulo-visual rehabilitation may work. 9/10
The good news is that vestibular asthenopia (tired and painful eyes, difficulty “scrolling” on screens) can also be fixed, by specialized vestibulo-visual rehabilitation. Which involves a rotating chair and weird 3D patterns…: 8/10
June 25, 2025 at 9:37 AM
The good news is that vestibular asthenopia (tired and painful eyes, difficulty “scrolling” on screens) can also be fixed, by specialized vestibulo-visual rehabilitation. Which involves a rotating chair and weird 3D patterns…: 8/10
Yet, during these 6 months, the brain started “ignoring” the vestibular system, and learned to only rely on the eyes for balance. As soon as the vestibular system worked again, this caused something known as “vestibular asthenopia”: pubmed.ncbi.nlm.nih.gov/34556339/ 7/10
Vestibular asthenopia - PubMed
Vestibular asthenopia, analogous to visual asthenopia, is a sensory (or sensory-motor) discomfort consisting of a set of subjective symptoms, the expression of which is essentially visual and whose or...
pubmed.ncbi.nlm.nih.gov
June 25, 2025 at 9:37 AM
Yet, during these 6 months, the brain started “ignoring” the vestibular system, and learned to only rely on the eyes for balance. As soon as the vestibular system worked again, this caused something known as “vestibular asthenopia”: pubmed.ncbi.nlm.nih.gov/34556339/ 7/10
The treatment was remarkably simple: placing a ventilation tube, to counteract the movement of the eardrum. After 6 months, the dizziness instantly disappeared. 6/10
June 25, 2025 at 9:37 AM
The treatment was remarkably simple: placing a ventilation tube, to counteract the movement of the eardrum. After 6 months, the dizziness instantly disappeared. 6/10
In this particular patient (me), dizziness only occurred during breathing. It turned out that the “open” eustachian tube made the eardrum move, triggering the inner ear (vestibular system), causing dizziness. 5/10
June 25, 2025 at 9:37 AM
In this particular patient (me), dizziness only occurred during breathing. It turned out that the “open” eustachian tube made the eardrum move, triggering the inner ear (vestibular system), causing dizziness. 5/10
The eustachian tube is a connection between your nose and ear. It is typically closed, and only opens briefly to equalize pressure (e.g. when you’re flying). But sometimes it stays open: a patulous eustachian tube. 4/10
June 25, 2025 at 9:37 AM
The eustachian tube is a connection between your nose and ear. It is typically closed, and only opens briefly to equalize pressure (e.g. when you’re flying). But sometimes it stays open: a patulous eustachian tube. 4/10
Quick summary: COVID-19 can cause dizziness by triggering a “patulous eustachian tube”, which can be fixed by placing a ventilation tube in your eardrum. Wait, a patulous what…? 3/10
June 25, 2025 at 9:37 AM
Quick summary: COVID-19 can cause dizziness by triggering a “patulous eustachian tube”, which can be fixed by placing a ventilation tube in your eardrum. Wait, a patulous what…? 3/10
Disclaimer: we think that cases like this are rare. Yet, if you do suffer from this, the good news is that the cause of dizziness could be easily fixed by an ear nose and throat doctor (and some specialized vestibular physiotherapy). 2/10
June 25, 2025 at 9:37 AM
Disclaimer: we think that cases like this are rare. Yet, if you do suffer from this, the good news is that the cause of dizziness could be easily fixed by an ear nose and throat doctor (and some specialized vestibular physiotherapy). 2/10