imunotolerância

Imunotolerância, also known as immune tolerance, is a state in which the immune system recognizes and coexists with specific antigens or tissues without mounting an adverse immune response. This phenomenon is a crucial aspect of immune regulation, preventing the body from attacking its own cells and maintaining tissue homeostasis.

There are various types of immunotolerance. Central tolerance occurs during lymphocyte development in primary lymphoid organs, such as the thymus and bone marrow, where self-reactive immune cells are eliminated or inactivated. Peripheral tolerance regulates immune responses to antigens that escape central tolerance mechanisms, ensuring that immune cells do not react against harmless antigens or self-antigens in the tissues.

Immunotolerance plays a vital role in pregnancy, allowing the maternal immune system to tolerate the semi-allogeneic fetus. It is also important in transplantation medicine, where inducing tolerance can prevent graft rejection. Conversely, a breakdown in immunotolerance can result in autoimmune diseases, where the immune system attacks the body's own tissues, or allergies, where it responds inappropriately to harmless substances.

Mechanisms involved in establishing and maintaining immunotolerance include the activity of regulatory T cells, deletion or anergy of reactive lymphocytes, and the production of immunosuppressive cytokines such as IL-10 and TGF-β. Research into immunotolerance is ongoing, with implications for therapies in autoimmunity, transplantation, and cancer.

Understanding immunotolerance is essential for developing strategies that modulate immune responses, aiming to enhance immune acceptance in transplants or suppress undesirable immune activity in autoimmune conditions.