Are there changes in blood cells among the causes of Long Covid?

Patient and sometimes healed red blood cells vary in size and are stiffer and less deformable even once the patient is healed. These and other changes in blood cells could partly explain Long Covid

(photo: Gerd Altmann via Pixabay) Long Covid, the prolonged aftermath of the disease, has been talked about for some time, although the causes are still unclear. One of the main hypotheses sees an involvement of the immune system. Today a study conducted by German biophysicists goes into the merits of the mechanisms that could change the activity of the immune system for a long time. In fact, the researchers found changes in the blood cells, red blood cells and white blood cells of patients who have or have had Covid-19. And these anomalies could play a role in the prolongation of symptoms. The work, led by a group from the Max Planck Institute for the Science of Light together with the Max Planck Institute for Physics and Medicine, is published in the Biophysical Journal. The results still concern a small sample of patients, although they pave the way for new more in-depth research and, if confirmed, could in the future, according to the authors, be used as biomarkers of Covid-19.

Studying the shape and properties of blood cells

The biophysicists involved 31 patients who had or who had had Covid-19, of which 14 with a very severe form in progress and 17 already healed, together with 24 healthy volunteers who had not had Covid and showed no signs of the disease. After the blood sample, the authors analyzed the characteristics of the main blood cells, erythrocytes (or red blood cells), monocytes, lymphocytes, neutrophils and eosinophils, through the analysis of various physical parameters. The technique used is (relatively) new and is called real-time deformability cytometry (Rt-Dc) and allows you to analyze hundreds of blood cells per second, detecting any abnormalities in size and structure.

Changes sometimes persist

"We found significant changes in lymphocyte hardness, monocyte and neutrophil size, neutrophil deformability, and a variability in erythrocyte deformation and size," the authors write in the text . "While some of these changes returned and the values ​​returned to normal at the end of hospitalization [with the recovery from Covid-19 ed], others remained for 14 months after discharge from the hospital, a demonstration of the long-term effects of Covid -19 on the body ". Eosinophils, on the other hand, were not affected by Covid, at least in these patients.

Beware of red blood cells

The greater variability of red blood cells (erythrocytes) in size and decreased deformability , with a more rigid structure, which could impact their ability to carry oxygen through the body and release it into tissues. "The physical properties of erythrocytes are essential for microcirculation", they also write in the publication, "and for this reason these changes could damage circulation and promote hypoxemia", that is, a lower than normal level of oxygen in the blood. These red blood cell changes have not returned, at least not entirely, to the healed and scientists speculate that this effect may contribute to the long-term symptoms of Long Covid.

But also to white blood cells

The changes in the infection would also affect monocytes, a type of white blood cell that participates in the immune response in some inflammatory diseases. For this presence of a variation in these cells "not surprising", as the researchers explain. In particular, there is a sharp increase in their volume. Among the white blood cells we then have the lymphocytes, which unlike the red blood cells in the analyzed sample were less rigid, and the neutrophils, which showed a greater volume and deformation. In severe Covid-19 cases, there was a high number of neutrophils (neutrophilia) and a low amount of lymphocytes (lymphopenia). In particular, the parameters of the neutrophils had not returned to normal in the recovered patients and this, together with the other results, indicates that the influence of Covid-19 on the immune system can persist for a long time. The researchers conclude that "deformability cytometry data could be used as biomarkers of Covid-19 and potentially other infectious diseases." In the future, they venture, the Rt-Dc technique could be part of the first line of defense against an unknown virus during another pandemic (always hoping it isn't there).


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Coronavirus Long Covid globalData.fldTopic = "Coronavirus, Long Covid"

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