Long Covid, among the causes of blood cell changes?

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)

Of Long Covid, the prolonged aftermath of the disease has been talked about for some time, although the causes are still there they are not clear. One of the main hypotheses sees a involvement of the immune system. Today a study conducted by German biophysicists goes into the merits of the mechanisms that could modify the activity of the immune system for a long time. The researchers, in fact, have found some alterations in blood cells, in red blood cells and white blood cells, of patients who have or have had Covid-19. And precisely these anomalies could play a role in the protracted symptoms. The work, led by a group from the Max Planck Institute for Light Science together with the Max Planck Institute for Physics and Medicine, is published its 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 biomarcatori of Covid-19.

Studying the shape and properties of blood cells

Biophysicists have involved 31 patients who had or had had Covid-19, of which 14 with a very serious form in progress and 17 already healed, together 24 healthy volunteers who had not had Covid and showed no signs of the disease. After withdrawal of blood, 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 the hardness of lymphocytes, in the dimension of monocytes and gods neutrophils, in the deformability of the neutrophils and a variability in the deformation and size of the erythrocytes, the authors write in the text. “While some of these changes returned and the values ​​returned to normal at the end of hospitalization [con la guarigione da Covid-19 ndr], others remained for 14 months after discharge from the hospital, a demonstration of the long-term effects of Covid-19 on the body ”. The eosinophils, on the other hand, were not affected from Covid, at least in these patients.

Beware of red blood cells

The greater variability of the Red blood cells (the 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 the tissues. “The physical properties of erythrocytes are essential for microcirculation, they always write in the publication, “And for this reason these changes could damage circulation and promote hypoxemia”, or a lower blood oxygen level than normal. These red blood cell changes did not return, at least not completely, to the healed and scientists speculate that this effect may contribute to long-term symptoms in LongCovid.

But also to white blood cells

The alterations of the infection would also concern the monocytes, a type of White blood cells which participates in the immune response in some inflammatory diseases. For this there is 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 i lymphocytes, which unlike the red blood cells in the analyzed sample were less rigid, ei neutrophils, which showed greater volume and deformation. In severe Covid-19 cases there was a high number of neutrophils (neutrophilia) and one low amount of lymphocytes (lymphopenia). In particular, the parameters of the neutrophils did not return 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 Covid-19 biomarkers and potentially other infectious diseases “. In the future, they venture, the technique Rt-Dc it could be in the first line of defense against an unknown virus during another pandemic (always hoping that there is not).

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