Pathophysiological mechanisms leading to low platelet count in immune thrombocytopenia

Abstract

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by the decrease in peripheral blood platelet count below 100 x 109/L, and an increased bleeding risk when thrombocytopenia drops below 30 x 109/L. The mechanisms leading to ITP in adults, although not completely elucidated, involves an imbalance between effector and regulatory cells that results in a breakdown of the immune tolerance. Autoantibodies are considered the main responsible for thrombocytopenia, although direct T-cell cytotoxic effect and lysis by Complement attachment and activation could also contribute to platelet elimination from circulation. In addition to increased peripheral clearance, abnormalities in platelet production also favors platelet count reduction. This review is intended to describe some specific knowledge about peripheral and bone marrow mechanisms leading to thrombocytopenia in adult ITP.