Drugs that target protein kinases have had a major impact on the treatment of cancer and now are proving beneficial in numerous immunological diseases. This Review describes their clinical application, with a focus on Janus kinase inhibitors, and how they inform mechanisms of disease and have evolved to improve efficacy and safety.

In this Review, the authors consider how early-life environmental exposures shape the immune system. They highlight how diet, medicines and other environmental factors influence the establishment of the gut microbiota and can impact susceptibility to allergic disease development.

In this Perspective, Honjo and co-workers describe the discovery of PD1 and its journey to become a major target for cancer immunotherapy. It discusses the complex regulatory systems that govern PD1 expression as well as recent insights into PD1 function and the mechanisms of PD1-blocking therapies.

IgG4 has unique functional characteristics that are increasingly recognized to have a pathogenic role in autoimmunity, tumour immunology, IgG4-related diseases and anti-biologic responses, as well as a beneficial role in allergy and parasitic infections.