Blood type transfusion can be considered safe as long as the serum of the recipient does not contain antibodies for the blood cell antigens of the donor. The "ABO system" is the most important blood-group system in human-blood transfusion. The associated anti-A and anti-B antibodies are usually "immunoglobulin M", abbreviated IgM, antibodies. ABO IgM antibodies are produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses. The original terminology used by Karl Landsteiner in 1901 for the classification was A/B/C; in later publications "C" became "O". Type O is often called "0" ("zero", or
Jehovah's Witnesses and blood transfusions Jehovah's Witnesses and blood transfusions Jehovah's Witnesses believe that the Bible prohibits ingesting blood and that Christians should not accept blood transfusions or donate or store their own blood for transfusion. The belief is based on an interpretation of scripture that differs from that of other Christian denominations. It is one of the doctrines for which Jehovah's Witnesses are best known. Jehovah's Witnesses' literature teaches that their refusal of transfusions of whole blood or its four primary components—red cells, white cells, platelets and plasma—is a non-negotiable religious stand and that those who respect life as a gift from God do