The innate immune system is tasked with rapid identification and response to immune threats, but acts with limited specificity against potential invaders. The acquired immune system, on the other hand, benefits from immune memory, and has a highly-tailored response to specific targets. However, ramping up specialized immune cell populations and aiming their efforts takes time. In effect, the innate response is quick and sensitive, yet is not specific, while the acquired response is highly specific yet somewhat delayed. To optimize the efficiency and efficacy of an immune response, these divisions of the greater immune system actively and intensively share information.
In regard to the major immune cell populations of the innate immune system:
● Macrophages surveil organs for the presence of immune threats that have
pathogen-associated molecular patterns (PAMPs) they recognize. This recognition process polarizes macrophages into an M1 phenotype that engulf invaders through phagocytosis and subject them to biochemical attack and breakdown. M1 macrophages secrete proinflammatory cytokines and chemokines that recruit other immune cells to join the protective response. M1 macrophages also ‘present’ antigens from neutralized pathogens to T and B cells of the acquired immune system. Once an immune threat is addressed, macrophages are transformed into the M2 phenotype that secrete immune-modulating interleukin-10 (IL-10) and transforming growth factor-beta (TGFβ) and facilitate healing and tissue renormalization. M2 macrophages tend to encourage T cell differentiation into regulatory T cells.
● Neutrophils are the most numerous white blood cells, and most neutrophils are found in circulating blood. Neutrophils are the first immune cells summoned in an inflammatory response, and they, in turn, can trigger naïve T cells of the acquired immune system to transform into T-helper cells. Neutrophils produce reactive oxygen species (ROS) to break down pathogens and present antigens to B cells. Neutrophils can metabolize omega-3 fats into lipid mediators, and are highly responsive to both parent and metabolite species.
In regard to the major immune cell populations of the acquired immune system:
● T cells are a diverse set of lymphocytes that originate in the thymus. T cells recognize the molecular patterns of pathogens presented by macrophages and dendritic cells of the innate system and organize a specific immune response. T cells are named according to their cell markers and functional roles: cytotoxic T cells carry the CD8 cell marker and help eliminate pathogen-affected cells, while T-helper cells carry the CD4 cell marker and may differentiate into Th1, Th2, Th3, Th9, Th17, Th22, or regulatory T cells, depending on the immune environment in which they develop. T-helper cells secrete specific arrays of cytokines that regulate the function of specialized immune cell populations, while regulatory T cells suppress immune cell activation by secreting IL-10 and TGFβ.
● B cells are lymphocytes that originate in bone marrow. B cells recognize molecular patterns of pathogens presented by macrophages and neutrophils, and produce antibodies and cytokines to aid the development of a specific immune response and catalog immune memories. B cells may also independently bind PAMPs, and certain B cells can act as antigen-presenting cells.
Omega-3s Coordinate Innate and Adaptive Immune Teamwork
The immune response is intricately choreographed and is extremely adaptive to changing conditions through rapid coordination of highly-specialized immune cell populations. Omega-3 fatty acids and their metabolites are known to directly influence the development and function of all immune cells so studied, and generous dietary intakes of these essential lipid mediators may alter the immune response in numerous immune-mediated health conditions.