Microglia is an important integral component of the neuro-glial cell network. They are present in the brain parenchyma from the early stage of development to the mature state. Microglia play an important role in brain immune surveillance. They can present antigens in the molecular context of MHC class II expression to CD-4 positive T cells. They are also capable of Fc-mediated phagocytosis, and share many common antigens with hemopoietic and tissue macrophages. Upon activation, they act as brain macrophages to clear tissue debris, damaged cells, or microbes when programmed cell death occurs during brain development or when the CNS is injured. Immortalized Human Microglia Cell Line also allow to stablish in vitro models for HIgh Throughput and High Content Screening.

Furthermore, there is evidence that microglia are related in a variety of physiological and pathological processes in the brain through interaction with neurons and other glial cells. They also produce a variety of biologically active substances; such as growth factors and cytokines.