Two recent studies led by Columbia University researchers shed light on why babies are more susceptible to common respiratory infections and how they cope with new pathogens. The research identified a unique cluster of immune cells found only in babies, providing insights into the development of their immune systems.
One study, published in Immunity, found that memory T cells, which play a crucial role in immune responses, accumulate rapidly in the lungs and intestines of babies up to age 3, but only become functionally mature by ages 4 to 6. This explains why young children are more vulnerable to recurrent respiratory infections compared to adults.
In contrast, the second study, published in Nature Immunology, discovered a "secret weapon" in babies' lungs—a specialized cluster of antibody-producing B cells surrounded by T cells, known as bronchus-associated lymphoid tissue (BALT). BALT helps babies respond to new pathogens before their memory T cells fully mature. This may explain why children are more resilient to new respiratory infections, including SARS-CoV-2.
These findings also offer insights into the development of chronic asthma and allergies in some children and may have implications for vaccine development. The research highlights the importance of childhood vaccines in protecting against infectious diseases and underscores the need to better understand the immune system's development throughout life.