The immune system of children: the key to understanding SARS
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Children are more vulnerable to other infections; thus, the important question arises—why are children less susceptible to COVID-19 disease compared to adults? So far, there is no evidence of a lower degree of expression or function of the SARS-CoV-2 receptor (namely ACE2) in children. Thus, studying the innate immune system of children might be the key to understanding protection against or susceptibility to SARS-CoV-2.

The immune preparedness of children to any novel pathogens, including, SARS-CoV-2 might be based on several factors:

First, in the early phases of infection, natural antibodies play a most important role. Natural antibodies, mostly of IgM isotype and generated independently of previous antigen encounters, have a broad reactivity and a variable affinity. They contain the infection during the 2 weeks necessary for production of high-affinity antibodies and MBCs that will clear the virus and prevent reinfection.

Second, children have the ability to rapidly produce natural antibodies of broad reactivity that have not yet been selected and shaped by the reaction to common environmental pathogens. Following infection, two types of MBC, CD27dull and CD27bright MBCs, cooperate.

Third, when a novel pathogen challenges the immune system, CD27dull MBCs might play a crucial role being capable of a more rapid reaction than naive B cells. They could immediately secrete antibodies and simultaneously enter the germinal centre reaction, where they acquire more somatic mutations and select their BCR on the basis of affinity. In infants and children, most MBCs are CD27dull and thus highly adaptable to new antigens.

In contrast, in the elderly, most MBCs are CD27bright. CD27bright MBCs, being highly mutated and specific, recognise their targets but appear incapable of adaptation to new antigens.

Although vaccines are the way forward, in emergency situations such as the COVID-19 pandemic, the investigation and use of immune tools that nature has endowed to children might improve management outcomes.

Dr. T●●●●z H●●●●●●i and 10 others like this6 shares
Dr. S●●●●●m S●●●●y P●●●●●l
Dr. S●●●●●m S●●●●y P●●●●●l General Medicine
This is wonderful news,especially in such a bleak times such a positive news was necessary.
May 26, 2020Like