November 30th: Cross-reaction with other coronaviruses is not good, it is harmful


Severe courses due to immune memory?

If it was previously assumed that previous contact with other coronaviruses helped the immune defense against Sars-CoV-2, a research team from Kiel found the opposite. It also explains why younger people tend to have slight gradients more often.

People who have not yet been infected with the new coronavirus also have so-called “T memory cells”. Although they recognize the virus, they are often overwhelmed. Difficult courses are the result.

In the course of life, the immune system’s memory stores how it effectively combats which pathogen. If the body comes into contact with the same pathogen a second time, the immune memory can fall back on existing knowledge in order to fight it off quickly and effectively.

Prof. Alexander Scheffold and Prof. Petra Bacher from the Institute for Immunology at Kiel University Hospital have examined to what extent previous contact with other coronaviruses favors a mild course of Sars-CoV-2, i.e. a cross-reaction can possibly be supportive.

For this purpose, immune cells from the blood of previously uninfected people were examined. The realization: the older the person, the greater the repertoire of immune memory. Scheffold and Bacher therefore speak of “immunological age”, which increases with age. “Rather, it seems to be the case that in the course of life the repertoire of memory cells against many different pathogens grows and thus the probability that some of them will also recognize Sars-CoV-2 by chance.”

However, there is a crucial catch: the memory cells can recognize Sars-CoV-2, but cannot fight it effectively. A trait that unites people without previous infection and people with severe disease.

In many cases, they are also of a higher immunological age and thus a higher probability that the immune system will fall back on these ‘incompetent’ memory cells.

Prof. Petra Bacher, University Medical Center Schleswig-Holstein

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