In a study published in the journal Immunity, researchers from the Institut Pasteur, the Bicêtre AP-HP hospital and the CNRS report the discovery of a new group of B lymphocyte-type immune cells, present only in infants, and constituting the preferred target of the virus of bronchiolitis. This study thus explains why this infection of the lower respiratory tract mainly affects newborns, all the more severely when they are young.
It particularly affects babies under 3 months
First cause of consultation andhospitalization in pediatric wardsin winter, bronchiolitis is an infection caused by the respiratory syncytial virus (RSV), affecting the lower respiratory tract. But, while adults or children over two years old are not affected by the virus very much, infants are particularly susceptible. Newborns under 3 months of age are particularly prone to developing very severe bronchiolitis.
The researchers therefore discovered why RSV particularly affected them. They identified a group of B lymphocytes, never described before, present only in very young children (less than one year) and which the RSV virus preferentially infects.
Objective: detect infants at risk from birth
B lymphocytes are cells of the immune system. They generally play a protective role against infections by producing antibodies. But the particular B cells discovered by scientists tend to reduce the response to the virus, which explains the increased severity of the disease.
“Our work explains the underlying, long-unrecognized reasons for infants’ susceptibility to bronchiolitis.”, comments Richard Lo-Man of the Institut Pasteur. “By identifying these new B lymphocytes as prognostic biomarkers of the severity of the disease, it should ultimately make it possible to detect risk areas at birth, and help the medical profession to develop more suitable treatments“.
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