Neutrophils play important roles not only in innate immune responses but also in acquired immune responses. As newly defined professional antigen presenting cells (APCs), neutrophils can present antigens to T cells and induce T cell differentiation. Splenic neutrophils have also been shown to support T cell-independent antibody responses by direct activation of marginal zone (MZ) B cells. A subset of human neutrophils with phenotype of CD11c^bright/CD62L^dim/CD11b^bright/CD16^bright can suppress T cell activation in response to acute inflammation. These new findings about neutrophils can help us to better understand the mechanisms of chronic inflammatory diseases, autoimmune diseases, and cancer, and may also eventually contribute to the discovery of new therapy targets for these diseases.