Durable and controlled depletion of neutrophils in mice

Neutrophils are an essential part of the innate immune system. To study their importance, experimental studies often aim to deplete these cells, generally by injecting anti-Ly6G or anti-Gr1 antibodies. However, these approaches are only partially effective, transient or lack specificity. Here we report that neutrophils remaining after anti-Ly6G treatment are newly derived from the bone marrow, instead of depletion escapees. Mechanistically, newly generated, circulating neutrophils have lower Ly6G membrane expression, and consequently reduced targets for anti-Ly6G-mediated depletion. To overcome this limitation, we develop a double antibody-based depletion strategy that enhances neutrophil elimination by anti-Ly6G treatment. This approach achieves specific, durable and controlled reduction of neutrophils in vivo, and may be suitable for studying neutrophil function in experimental models. Anti-Ly6G or ant-Gr1 antibodies are commonly used to deplete neutrophils in vivo. Here the authors provide mechanistic insight into why these approaches may not specifically or durably reduce the number of neutrophils in mice, and also present a new method that overcomes these limitations to have potentially wide applicability in experimental studies.