Macrophages are important effector cells in the human immune system and are found in almost every tissue in the human body. They are crucial to functioning of both the innate and adaptive elements of the immune system with different, but related, macrophage types both activating and suppressing the immune response as well as being involved in wound healing and secretion of regulatory cytokines. Selective targeting of macrophages can thus be used to affect the activation status of the immune response to treat diseases in which the immune system is either malfunctioning or imbalanced.