A rare type of white blood cell has been shown to play an important role in long term immunity to infections. A new study, online this week in Nature Immunology, shows that basophils, which constitute less than one percent of total white blood cells circulating throughout the body, could play a key role in the prevention of streptococcus infections. Basophils are mainly associated with release of histamine and other factors linked to allergic reactions and to defence against parasites.
Matthias Mack and co-workers find that basophils detect foreign molecules produced by pathogens. During subsequent infections basophils ‘remember’ the previous pathogen encounter and then release chemical mediators called interleukin 4 and interleukin 6. These factors help other immune cells called B lymphocytes produce antibodies that attack and destroy the pathogen. Mice with reduced numbers of basophils, for example, are significantly more susceptible to streptococcus infection, which causes meningitis, pneumonia and ‘flesh-eating’ diseases.
Although previous work had shown the importance of interleukins 4 and 6 for antibody production, the source of these signalling molecules was not heretofore attributed to this least common of the leukocytes?the basophil.