On the basis of the mechanisms of action and characteristics of immune
effects, immunity is generally divided into innate and adaptive
immunity. Adaptive immunity is associated with the response to non-self
entities and is characterized by high specificity and memory. In
contrast, innate immunity is believed to lack memory. However, an
increasing number of studies have sought to challenge this traditional
immunological dogma and have shown that innate immune cells respond to
secondary stimulation more strongly and rapidly than to the primary
triggers, thus providing evidence of the immune memory in innate
immunity. Macrophages, which are among the most important innate immune
cells, can also acquire memory that facilitates the mediation of recall
responses. Macrophage memory is a relatively new concept that is
revolutionizing our understanding of macrophage biology and
immunological memory and could lead to a new class of vaccines and
immunotherapies. In this review, we describe the characteristics and
mechanisms of macrophage memory, as well as its key roles in various
diseases.