When it comes to treating disorders in which dysregulated immune responses play a significant role, immunotherapy is a game-changer. The adaptive immune system is the focus of most ongoing immunotherapy research and development. Metabolic and epigenetic programming have revealed long-term alterations in the functional programme of myeloid (monocytes, macrophages, and dendritic cells) and lymphoid (natural killer cells, and innate lymphoid cells) cell populations of the innate immune system in the previous decade. The immune response to secondary stimuli can be altered by reprogramming these cells to be either hyperresponsive or hyporesponsive.