Recent research has unveiled why infants are more susceptible to respiratory infections due to their not-yet-matured memory T cells. However, babies also possess a distinctive defense mechanism known as bronchus-associated lymphoid tissue (BALT), responsible for producing antibodies against new pathogens. This tissue fades away after the age of three.
Two separate studies conducted by Columbia University researchers have provided insights into the reasons behind the high occurrence of common respiratory infections in babies. The research, led by Donna Farber, Ph.D., an expert in immune system development, used tissue samples from deceased pediatric organ donors to identify differences in the immune system development between babies and adults.
One study, published in Immunity, discovered that memory T cells, crucial for mounting a specific immune response, accumulate rapidly in the lungs and intestines until age three but only develop protective immunity around ages 4 to 6 years. This explains why young children are more vulnerable to recurrent respiratory infections compared to adults.
The second study, published in Nature Immunology, revealed that babies possess a unique strategy for dealing with new pathogens. The researchers found clusters of B cells producing antibodies, surrounded by T cells, in infants’ lungs. This BALT develops between 6 and 12 months of age but disappears after age 3. This mechanism enables young children to respond effectively to the various respiratory pathogens encountered early in life, making them more resilient to new infections like SARS-CoV-2.
The findings may also offer insights into severe food allergies and chronic asthma in children and could explain why certain vaccine types work better in children than in adults. While BALT provides some protection, childhood vaccines remain crucial for safeguarding children from infectious diseases. The studies were supported by grants from the National Institutes of Health and the Helmsley Charitable Trust.
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Frequently Asked Questions (FAQs) about Infant Immunity
1. What does the new research reveal about infant susceptibility to respiratory infections?
The new research explains that infants are more susceptible to respiratory infections due to their yet-to-mature memory T cells. These cells are not functionally mature until around ages 4 to 6 years, making babies and young children more vulnerable to infectious diseases compared to adults.
2. What is bronchus-associated lymphoid tissue (BALT), and how does it protect infants?
BALT is a unique defense mechanism found in babies. It is a cluster of antibody-producing B cells surrounded by T cells in the lungs. It helps infants cope with new pathogens by producing antibodies against respiratory pathogens early in life, making them more resilient to infections.
3. How did the researchers conduct the studies?
The researchers conducted the studies at Columbia University using tissue samples from deceased pediatric organ donors. This allowed them to pinpoint differences in immune system development between babies and adults.
4. What might explain the low severity of COVID-19 in babies and young children?
The presence of bronchus-associated lymphoid tissue (BALT) in infants may explain why they were less susceptible to severe COVID-19. BALT enables an early immune response to new respiratory pathogens, including SARS-CoV-2, that adults may lack.
5. How could the research findings impact vaccine development?
The research provides insights into why intranasal influenza vaccines tend to work better in children. Understanding the role of BALT could potentially inform the development of more effective vaccines for certain age groups.
More about Infant Immunity
- “Immunity” (Study 1): https://doi.org/10.1016/j.immuni.2023.06.008
- “Nature Immunology” (Study 2): https://doi.org/10.1038/s41590-023-01557-3
- Columbia University Vagelos College of Physicians and Surgeons: https://www.ps.columbia.edu/
