HIT occurs when the body's immune system generates antibodies against complexes formed by heparin and platelet factor 4 (PF4). These antibodies activate platelets, leading to their removal from the bloodstream (thrombocytopenia) and paradoxically, to the formation of blood clots. There are two types of HIT: Type I, a non-immune, mild, and transient reduction in platelets, and Type II, an immune-mediated and more severe condition.
