Why Do We Have Different Blood Types?
January is National Blood Donor Month, a time of interest to more than just the Medical Laboratory Technician. With a particularly blustery winter, record levels of flu cases and busy holiday seasons, donation levels are dangerously low in some parts of the country. âWe saw over 300 blood drives across 27 states over the last month and a half due to the weather resulting in 10,500 fewer donations than we were expecting,â said American Red Cross District Manager in Blood Services Kelly Weber in an interview with Lansing, Mich.-based WLNS TV. In Fresno, Calif., blood banks there are reporting 30-year lows for their stockpiles. The Red Cross, Community Blood Centers and local hospitals are in need of every blood type. Which got us thinking â¦ .
Why are there so many blood types?âBlood types are made up of antigens,â explains Diana Riddle, Medical Laboratory Technician Instructor at Concorde-Memphis. âAntigens are proteins that act as identifiers on our red blood cells (and all of the cells in the body). It is how our bodies identify âself.â It is this ability to distinguish self from ânon-selfâ that enables the immune system to defend the body.â The most common blood types are A, B, AB and O. According to Riddle: A personâs blood type is based upon the absence or presence of the A and B antigens (in the ABO blood system), therefore:
- If one has the A antigen, but not the B antigen, they are said to be type A
- If one has the B antigen, but not the A antigen, they are said to be type B
- If one has both the A and the B antigens, they are said to be type AB
- If one has neither the A nor the B antigen, they are said to be type O