Severe cases of Covid-19 do not produce a stronger immune response

Hyperaxion Aug 7, 2020

German scientists suspect that although immune cells are produced in large quantities in severe conditions, their function is defective.

Severe Covid-19 does not necessarily produce a stronger immune system reaction. This is the conclusion of a study, conducted by six research institutions in Germany, that will be published this month in the journal Cell.

Severe cases of Covid-19 do not produce a stronger immune response
(Credit: University of Minnesota).

The scientists analyzed blood samples from 53 men and women with mild or severe Covid-19. For the control group, blood samples were collected from patients with other viral infections of the respiratory tract and from healthy individuals.

The scientists analyzed gene activity and the amount of proteins at the cellular level, which enabled them to characterize the properties of white blood cells, which play an important role in the immune system.

“In combination with the observation of important proteins on the surface of immune cells, we were able to decipher the changes in the immune system of patients with COVID-19,” said Birgit Sawitzki, co-author of the study.

The study focused on myeloid cells, which include neutrophils and monocytes. These cells are mobilized very early to defend the body against infections. In addition, they influence the subsequent production of antibodies and other cells that contribute to creating immunity against a certain pathogen.

“We have found that these immune cells are activated, i.e. ready to defend the patient against COVID-19 in the case of mild disease courses. They are also programmed to activate the rest of the immune system,” said Antoine-Emmanuel Saliba, a member of the research team. “This ultimately leads to an effective immune response against the virus.”

However, the situation is different in severe Covid-19 cases. In these conditions, neutrophils and monocytes are only partially activated and do not function properly. “We find considerably more immature cells that have a rather inhibitory effect on the immune response,” said Leif Erik Sander, co-author of the research.

According to Sander, although the reason for this is still unknown, the phenomenon can also be observed in other serious infections. Particularly in the case of Covid-19, this mechanism can lead to an insufficient immune response to Sars-CoV-2 and the worsening of inflammation in the lung tissue.

“There is still not very much known about the causes of these severe courses of the disease. The high inflammation levels measured in those affected actually indicate a strong immune response. Clinical findings, however, rather tend to indicate an ineffective immune response. This is a contradiction,” said another co-author, Joachim Schultze.

They concluded, therefore, that although immune cells are produced in larger quantities, their function is defective. The team believes that these findings are very important for the development of treatments against the new coronavirus, especially those that focus on the immune system.

“Our data suggest that in severe cases of COVID-19, strategies should be considered that go beyond the treatment of other viral diseases,” said Anna Aschenbrenner, who also participated in the study.

Related topics:

Coronavirus Covid-19

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