Question

What antigens and antibodies determine blood type?

Answer 1

Blood type AB Rh- Antigens (on the surface of the red blood cells):
AB indicates there are both A and B antigens. (If there are A and B antigens but no Rh antigens, the antibodies in the blood plasma are Rh antibodies.)

Answer 2

Source:
http://www.nobelprize.org/educational/medicine/bloodtypinggame/1.html

These may also be helpful for more information:
http://anthro.palomar.edu/blood/ABO_system.htm

http://www.nobelprize.org/educational/medicine/landsteiner/readmore.html

Answer 3

The blood group antigen and antibodies are a bit counterintuitive in principal. E.g. If you are blood group A, you have A antigens on your red blood cells, but your blood serum does not contain any anti-A antibodies, or else that will be catastrophic and your blood will agglutinate (stick together). Different antigens on red blood cells just basically mean slight modifications to the glycoproteins on the surface of red blood cells. So for antigen A, the basic glycoprotein is modified with acetyl-galactosamine; antigen B modifies the basic glycoprotein by adding galactose. For people with blood group O, there are no modification of the glycoproteins, and for people of blood group AB, the red blood cells have both the acetygalactosamine and galactose added on the glycoproteins.