Most antigens are benign вЂ“ they wonвЂ™t hurt you if you receive blood that contains it. Some antigens are only found within certain racial or ethnic groups.

In addition to the four main ABO groups you may have heard of blood that is positive or negative.ДЄccording to the American Society of Hematology, there are 35 major groups of antigens besides A and B. Those with AB blood have both the A and B antigen so they can receive blood from anyone with type A, B or O blood. That means that it can be given to anyone without a problem because there are no new antigens being introduced that may stimulate an immune response. While type A and B blood types are fairly straight forward, O and AB are unique. Fortunately, Cumberland noted, an incompatibility reaction is very rare since strict protocols are in place at medical facilities to ensure patients receive the right type of blood. This immune response can lead to kidney damage or death if not treated right away. Your body will recognize blood with the same antigen and welcome it but if the donor blood has a different antigen, your body will treat the new blood as an invader and attack it. If you need a blood transfusion, it is important to get the right type. вЂњThese antigens donвЂ™t affect your health or the way your body functions, it is just a genetic difference like hair color or height,вЂќ said Josh Cumberland, lead medical lab scientist at Samaritan Albany General Hospital. The antigens in your blood and your blood type are determined by your genetics.

Type O blood has neither A nor B antigens.

Type AB bloodВ has both A and B antigens.

Type B blood has a B antigen on the red blood cells.

Type A blood has an A antigen on the red blood cells.

There are two antigens, A and B, that determine your blood group depending on if the antigen is present or absent. An antigen is a small protein that creates an immune response in your body. What determines your blood type is an antigen on the red blood cell. Why Are Blood Types Different?Д«lood is categorized into four main groups, A, B, AB and O. However, in the case of an accident or emergency it could be helpful to know your blood type.

Unless youвЂ™ve had a recent blood transfusion or pregnancy, there arenвЂ™t too many times you need to know this information. This mixing of blood can happen at various stages of pregnancy, including abortion.For most people, knowing your blood type isnвЂ™t at the top of your medical priorities. These вЂanti-DвЂ™ antibodies attack red blood cells with the D antigen on them.

If at any stage of pregnancy there is mixing of your RhD negative blood with that of the fetus which may be RhD positive, your bodyвЂ™s defence mechanism, called the immune system, may form antibodies against the D antigen. If the father of the pregnancy is RhD positive, then there is a chance that the fetus will also be RhD positive even if you are RhD negative. Whether someone is RhD positive or negative is inherited from both parents. People who are RhD negative do not have the D antigen on their red blood cells. People who are RhD positive have a substance called D antigen on their red blood cells. All rhesus negative women having a surgical abortion or medical abortion over 10 weeksвЂ™ gestation are offered an anti-D injection.ДЄs well as the main blood groups (A, B, AB or O) there is a second factor called rhesus (RhD).

Pregnancy a negative blood type