The Different Immune Responses by Age Are due to the Ability of the Fetal Immune System to Secrete Primal Immunoglobulins Responding to Unexperienced Antigens.
Int J Biol Sci
; 18(2): 617-636, 2022.
Article
in English
| MEDLINE | ID: covidwho-1689841
ABSTRACT
Among numerous studies on coronavirus 2019 (COVID-19), we noted that the infection and mortality rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) increased with age and that fetuses known to be particularly susceptible to infection were better protected despite various mutations. Hence, we established the hypothesis that a new immune system exists that forms before birth and decreases with aging. Methods:
To prove this hypothesis, we established new ex-vivo culture conditions simulating the critical environmental factors of fetal stem cells (FSCs) in early pregnancy. Then, we analyzed the components from FSCs cultivated newly developed ex-vivo culture conditions and compared them from FSCs cultured in a normal condition.Results:
We demonstrated that immunoglobulin M (IgM), a natural antibody (NAb) produced only in early B-1 cells, immunoglobulins (Igs) including IgG3, which has a wide range of antigen-binding capacity and affinity, complement proteins, and antiviral proteins are induced in FSCs only cultured in newly developed ex-vivo culture conditions. Particularly we confirmed that their extracellular vesicles (EVs) contained NAbs, Igs, various complement proteins, and antiviral proteins, as well as human leukocyte antigen G (HLA-G), responsible for immune tolerance.Conclusion:
Our results suggest that FSCs in early pregnancy can form an independent immune system responding to unlearned antigens as a self-defense mechanism before establishing mature immune systems. Moreover, we propose the possibility of new solutions to cope with various infectious diseases based on the factors in NAbs-containing EVs, especially not causing unnecessary immune reaction due to HLA-G.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Aging
/
Fetal Stem Cells
/
SARS-CoV-2
/
COVID-19
/
Immunity
Limits:
Female
/
Humans
/
Pregnancy
Language:
English
Journal:
Int J Biol Sci
Journal subject:
Biology
Year:
2022
Document Type:
Article
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