🩸What Are Blood Types A, B, O, and AB?

🔷 Not a Personality Test 😊

Blood types were never meant to be used for personality diagnosis. That idea is a cultural phenomenon mainly in Japan and Korea. In Japan, almost everyone knows their blood type, but in many other countries, people often don’t know unless they’ve had surgery or donated blood.

ABO blood groups are named after the antigens (markers) on the surface of red blood cells.

• People with type A have A antigens, so they do not have anti-A antibodies. Instead, they have anti-B antibodies.
• People with type B have B antigens, so they do not have anti-B antibodies, but they do have anti-A antibodies.
• Type AB has both A and B antigens, so they have no antibodies against A or B.
• Type O has neither A nor B antigens, so they make both anti-A and anti-B antibodies.

💡 One tip: “Like = no antibody” / “Dislike = antibody present.”
(By the way, the “O” in blood type comes from the German word ohne, meaning “none,” not the number zero.)

🔷 Explaining With “Idol Fan Clubs”

Imagine a school with two very popular boys, A and B. (Of course, there are other boys too, some more or less known — just like irregular antibodies. For example, “D” is fairly well-known.)

• Team A (type A): Fans of A. They dislike B and will “attack” him when they see him.
• Team B (type B): Fans of B. They dislike A and will attack him.
• Team AB (type AB): Big fans of both A and B, cheering for everyone.
• Team O (type O): They dislike both A and B, attacking both whenever they appear.

🔷 About Irregular Antibodies…

Since A and B are so famous, Team A dislikes B, Team B dislikes A, and Team O dislikes both. But other boys in school are not as famous.

For example, D (the RhD antigen) is like a family member for most people (about 85% are Rh positive). Everyone grows up with him, so nobody attacks him.

But some “transfer students” don’t know D (Rh negative, about 15% worldwide). They don’t hate him at first. But if D suddenly gets too friendly (through transfusion), they may start to dislike him and make antibodies against him.

📝 Summary

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Japanese version