Immune cells that protect against group A Streptococcus

A subset of immune cells can protect against the early phase of severe invasive group A Streptococcus infections reports a paper in Nature Communications this week. These findings suggest that the cells can compensate for a serious side effect of infection - neutropenia - the reduction in the number of white blood cells, known as neutrophils. Group A Streptococcus infections can range from mild symptoms, such as skin infections, to serious infections including toxic shock syndrome. Neutrophils and myeloid cells are important in protecting against such infections, but during severe infections neutrophils are reduced in number. Manabu Ato and colleagues identified a subset of myeloid cells with ring shaped nuclei that produce the signalling molecule, interferon-g. These cells are distinct from myeloid suppressor cells that also produce the interferon-g and the team noted that when the cells with ring-shaped nuclei were transferred into mice they could protect them from severe group A Streptococcus infection. However, administration of interferon-g was detrimental to mice in later stages of infection. Their findings suggest that this subset of cells is important for protecting against the early stages of group A Streptococcus infection.