Conclusion & perspectives
Trained or primed macrophages exhibit immune memory similar to that of
adaptive immunity when challenged with secondary triggers. There are two
types of macrophage memory, namely, trained and endowed immunity.
Trained
macrophages acquire memory via epigenetic and metabolic reprogramming,
induce trained immunity, and facilitate an altered immune response upon
secondary stimulation. Similarly, primed macrophages can acquire memory,
which leads to the development of endowed immunity and allogeneic
rejection in response to stimulation with the same allogeneic antigen.
The discovery of macrophage
memory has challenged traditional dogma regarding the limitations of
immunological memory and enriched our understanding of
macrophage-mediated immune responses. More importantly, unraveling
macrophage memory provides a more comprehensive perspective on the
pathogenesis of immune-mediated diseases, and may lead to establishing a
new class of vaccines and the development of novel immunoprophylactic
and therapeutic strategies.