Study Finds Sustained Cellular Immune Dysregulation in People Recovering from COVID-19

Coronavirus – PIXABAY/CSIC


Researchers at the University of Alabama at Birmingham (United States) have shown sustained cellular immune dysregulation in people recovering from an infection with SARS-CoV-2, the virus that causes COVID-19.

“The importance of these studies cannot be overemphasized to provide context for the interpretation of the immune responses elicited by participants in the COVID-19 vaccine trials, including how those responses change over time. information will be key in the possible modifications of the existing vaccines and treatments of COVID-19 “, explain the authors in a scientific article published in the journal ‘Journal of Clinical Investigation’.

The researchers obtained blood samples and clinical data from 46 patients hospitalized with the COVID-19 vaccine and 39 non-hospitalized people who had recovered from a confirmed COVID-19 infection. Both groups were compared to healthy, COVID-19-negative controls. It is important to note that most of the individuals in the hospitalized group had active SAR-CoV-2 viruses in their blood and were in the hospital at the time of sample collection. All individuals in the non-hospitalized group were convalescing at the time the sample was taken.

From the blood samples, the researchers were able to separate specific subsets of immune cells and analyze the markers on the cell surface. Using this complex information, immunologists can analyze how each individual’s immune system responds during infection and during convalescence. Some of these results can reveal whether immune cells have been activated and depleted by the infection. Depleted immune cells can increase susceptibility to secondary infection or hinder the development of protective immunity to COVID-19.

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In addition, the researchers were able to analyze changes over time, in two ways. The first was to observe the changes in surface markers over time, defined as the days elapsed since the onset of symptoms in the non-hospitalized samples. The second was by directly comparing the frequencies of these markers between the first and second clinic visits for out-of-hospital patients from whom blood samples were collected at two sequential time points.

The most surprising finding was that of outpatients. While the researchers observed increased activation markers in hospitalized patients, they also found that various activation and depletion markers were expressed with higher frequencies in outpatient convalescent samples.

By observing these markers over time, it was observed that immune dysregulation in non-hospitalized individuals did not resolve rapidly. Furthermore, dysregulation of T-cell activation and depletion markers in the outpatient cohort was more pronounced in the elderly. “To our knowledge, this is the first description of sustained immune dysregulation due to COVID-19 in a large group of non-hospitalized convalescent patients,” they detail.

The B and T cells of both patient cohorts had phenotypes consistent with cell activation and depletion throughout the first two months of infection. And in non-hospitalized individuals, activation markers and cell depletion increased over time. “These findings illustrate the persistent nature of the changes in the adaptive immune system that have been observed in COVID-19 and suggest longer-term effects that may inform the maintenance of immunity to SARS-CoV-2,” they conclude.

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