sentences:  After ingestion, these antibodies coat the red blood cells of the foal, leading to lysis through the complement system or removal by the mononuclear phagocyte system, and causing subsequent anemia.Most blood groups do not produce a highly immunologic response when the mare is exposed from previous foals or through placental leakage of red blood cells.However, a few factors, such as Aa and Qa, do lead to a significant response and therefore account for the majority of cases of isoerythrolysis.