Immune hemolytic anemia (IHA) is a type of hemolytic anemia in which the body's own immune system attacks and destroys red blood cells (RBCs). It is classified into two categories: primary IHA and secondary IHA.
Primary IHA
Primary IHA is a rare form of IHA in which the body produces autoantibodies that mistakenly target and attack its own RBCs. The most common types of primary IHA are warm autoimmune hemolytic anemia (WAIHA) and cold autoimmune hemolytic anemia (CAIHA).
WAIHA: WAIHA is caused by autoantibodies that are activated at normal body temperature (37°C). These autoantibodies bind to the RBCs and trigger a process called "complement activation" that leads to destruction of the RBCs.
CAIHA: CAIHA is caused by autoantibodies that are activated at cold temperatures (4-10°C). These autoantibodies bind to the RBCs and trigger a process called "cold agglutinin" that leads to the destruction of the RBCs.
Secondary IHA
Secondary IHA is a form of IHA in which autoantibodies are produced in response to an underlying condition, such as an infection, a drug, or a cancer. These autoantibodies mistakenly target and attack the body's own RBCs, leading to their destruction.
