INFLUENCE OF CD4 T LYMPHOCYTES DURING THE DEVELOPMENT AND MATURATION OF THE CENTRAL NERVOUS SYSTEM

The categorization of the central nervous system (CNS) as an immunoprivileged system began in the last century and, at the time, this classification was well accepted by the scientific community. However, the CNS is responsive to changes in the immune system and the opposite is also true. A CNS demand by the adaptive immune system seems to occur for adequate neurodevelopment, since the absence of lymphocytes in immunodeficient mice leads to impairment of CNS functionality. It was demonstrated that the T lymphocytes found in the brain parenchyma are necessary for the maturation of microglia, a fundamental process for the correct development of the CNS that can influence the control of anxiety, motivation and learning in adult animals. Proper CNS development depends on the organization of synaptic contacts that result in topographically organized maps. The formation of neural circuits extends into the postnatal period and depends on the stimulation of environmental factors and the cellular microenvironment, mainly during the so-called critical periods, which are temporal windows where molecular mechanisms of synaptic plasticity are considerably modulated by experience.