Functional aspects, phenotypic heterogeneity, and tissue immune response of macrophages in infectious diseases

de Sousa, Jorge Rodrigues; Da Costa Vasconcelos, Pedro Fernando; Quaresma, Juarez Antonio Simões

The primary function of the immune system has traditionally been defined as protection against microorganisms, although it plays an equally crucial role in protecting the host against invasion by foreign agents and eliminating affected cells that might compromise organic homeostasis. [1] [2] [3] [4] [5] The immune system functions through mechanisms involving both humoral and cellular immunity, which generally act in the early and late inborn phases of the response to antigens, respectively. [2] [3] [4] [5] In this context, the concept of organ-specific tissue immunity, which is related to the functional specificity of each organ mostly arose from the research of Engwerda and Kaye. 1 Particularly, in their study in 2000, the authors discussed the immunological mechanisms triggered in response to hepatic infection by parasites of the genus Leishmania. 1 This work helped focus attention on the concept of tissue immunity and prompted investigations into its mechanisms in various organs because of the close relationship between the induction routes of the cellular lesions involved in distinct organs in infectious, inflammatory, metabolic, and neoplastic diseases. 1 the skin, macrophages might be present as Langerhans cells or histiocytes, which primarily function in phagocytosis as well as antigen capture, processing, and presentation. 13, [21] [22] [23] [31] [32] [33]