In the human ABO blood group system, individuals with blood group AB have which combination of antigens and antibodies in their blood?

Introduction / Context:
The ABO blood group system is based on the presence or absence of specific antigens on the surface of red blood cells and naturally occurring antibodies in the plasma. Understanding these combinations is essential for safe blood transfusions. This question asks about individuals with blood group AB and what antigens and antibodies they have, which is directly related to the concept of universal acceptor.

Given Data / Assumptions:

• The group in question is blood group AB in the ABO system.
• Options mention presence or absence of antigens and antibodies.
• We assume standard ABO group rules without rare subgroups.
• Rh factor is not being considered in this question.

Concept / Approach:
In the ABO system, blood group A has A antigen on red cells and anti B antibody in plasma. Group B has B antigen and anti A antibody. Group O has no A or B antigens but has both anti A and anti B antibodies. Group AB has both A and B antigens on red cells but does not have anti A or anti B antibodies in its plasma. Because they lack these antibodies, AB individuals can receive red blood cells from any ABO group and are called universal recipients. The key point here is absence of antibodies, not absence of antigens.

Step-by-Step Solution:
Step 1: Recall the basic rule that antigens on red cells determine the ABO group, and antibodies in plasma are directed against missing antigens. Step 2: For group AB, red cells possess both A and B antigens. Step 3: Because the body does not form antibodies against its own antigens, AB individuals do not have anti A or anti B antibodies in their plasma. Step 4: This lack of anti A and anti B antibodies allows AB individuals to accept cells from any ABO group without immediate immune reaction. Step 5: Option B states that there is no antibody in plasma, which correctly reflects the absence of anti A and anti B in AB blood. Step 6: Options suggesting no antigen, neither antigen nor antibody, or both antibodies are inconsistent with the defining features of AB blood.

Verification / Alternative check:
Standard blood group tables list ABO phenotypes along with their antigens and antibodies. For AB, the table shows A and B antigens present on red cells and no corresponding anti A or anti B antibodies in serum. Compatibility charts show that AB recipients can receive from O, A, B, and AB donors because their plasma does not contain antibodies that would attack donor cells. This pattern confirms that absence of ABO antibodies in plasma is the correct feature of blood group AB.

Why Other Options Are Wrong:
Option A, no antigen on red blood cells, actually describes group O, which lacks A and B antigens. Option C, neither antigen nor antibody, does not match any normal ABO group. Option D, both A and B antigens and both antibodies, is impossible because an individual cannot safely have antibodies against antigens present on their own cells. Option E, only antibody A in plasma, does not match any ABO profile; group B has anti A, but it does not have both A and B antigens.

Common Pitfalls:
Some students confuse universal donor and universal recipient concepts and may think group O has no antibodies, while actually group O lacks antigens and has both antibodies. Others focus only on antigens and forget about antibodies. To avoid confusion, memorise a simple chart or use a mnemonic linking A with anti B, B with anti A, O with both, and AB with none. This makes it easier to answer questions about compatibility and antigens antibodies combinations.

Final Answer:
Individuals with blood group AB have both A and B antigens on their red cells and No antibody in plasma against these antigens.