The importance of polyreactive antibodies in protection against pneumococcal infection.

Antibodies are a key element of the immune response. They can bind their molecular targets with exquisite sensitivity and specificity, providing protection against a multitude of pathogens. They have long been understood to be markers of a successful response to vaccination, and are now widely manufactured as highly specific and robust immunotherapeutic agents. Less well understood are the polyreactive antibodies, found in serum, which are able to bind more than one target molecule. Here, we highlight new research into these naturally occurring polyreactive antibodies, which demonstrates their importance for protection against Streptococcus pneumoniae, a common cause of airway infection.