What is the difference between blood types?

I’m sure this question was asked at some point, but I never saw it nor did I see the answer. Can anyone fill me in? I’m talking about the difference between types such as Type A, O positive, etc.

I realize I’m generalizing here, but as in most cases, I don’t care.
-Dave Barry

From this site:

We gladly devour those who would subdue us.

Oh yeah, from the same site:

We gladly devour those who would subdue us.


Just to make sure I understood:

produces O?

And O as well if one B gene and an O gene?

Forget it, Alpha, I went to the site you linked and read (which I should’ve done before posting - sorry).

I think it might be useful to add that the various blood types are sometimes but not always okay for donation to one another. Basically, you can safely receive blood as long as it doesn’t have a “letter” that isn’t in your blood naturally. Since type-O doesn’t have either “letter”, everyone can receive blood from a type-O donor. Type-As can donate only to other type-As and type-ABs. Type-ABs can receive from anybody at all, those lucky ducks.

Don’t know how the Rhesus factor fits in though … is type-O positive the universal donor, or type-O negative, or both?

Woohoo! I’m AB+ !!!


The Legend Of PigeonMan - By Popular Demand! Enjoy, enjoy!

O-negative is the universal donor. O+ can donate only to other Rh-positive people.

Rick (Proudly pumping O- blood through my own veins for over 35 years!)

Rh factor was found when serum from Rhesus monkeys was added to blood from humans, and it was noted that some blood cells “agglutinated” when exposed to certain elements of the Rhesus blood. The “Rh factor” indicates whether your blood would agglutinate (+) or would not (-). The precise chemistry which causes this, was not known at the time the identification was made. The correlation with severe reactions was known, and the factor was adopted as a useful test to eliminate probable bad matches.

It was soon also noted that many handicapped children who were Rh+ were second children born to women who were Rh-. Further investigation revealed that all such children had fathers who were Rh+, as well. (I might have that reversed, but I think it is right.) Eventually it was learned how to prevent the harm done to both mother and child in that case, with medications.


Thou shalt not answer questionnaires
Or quizzes upon world affairs,
Nor with compliance
Take any test. Thou shalt not sit
with statisticians nor commit
A social science.
– **W H Auden **

How do you go about finding out your blood type? Is it on record with your doctor? Also, why would you want to disable smilies on a post? Just a side note.

I’m A+.

As I read this, that means I could receive only O- or O+, yes?

  • Rick

You could also receive A positive blood, and if I’m reading this correctly, A negative blood as well.

Keep in mind that the doning limitations are for whole blood only; I think anybody can receive plasma from anybody, since they take all the other stuff out in a centrifuge. So if you are an AB positive person, and you are feeling socially responsible, it would probably better to donate plasma since your whole blood wouldn’t be especially useful.

The people at the Red Cross explained it to me by saying “Think of blood types as being added together.” O + O = O, O + A = A, O + B = B, O + AB = AB, A + A = A, A + AB = AB, B + B = B, B + AB = AB and AB + AB = AB.

For Rh factors ‘-’ + ‘-’ = ‘-’, ‘-’ + ‘+’ = ‘+’ and ‘+’ + ‘+’ = ‘+’.

When receiving blood, you can accept any blood type as long as it and your own blood “add up” to the type you already have.

For example, if you are B+ you can receive O- because B+ + O- = B+. You cannot receive A- because B+ + A- = AB+ (which isn’t you).

I’m A- which is one of the ones they seem to like getting. My mother is O-; true universal donor but can only receive O- blood.

“Drink your coffee! Remember, there are people sleeping in China.”

Dennis Matheson — dennis@mountaindiver.com
Hike, Dive, Ski, Climb — www.mountaindiver.com

I know, casually, someone who works for the Red Cross. From various things he’s said I’ve pieced together that while theoretically you could just give O- blood to everyone, in practice they seem to strongly prefer using actual matches. Whether this is to preserve O- for people who really NEED that and nothing else, or if there’s some other reason, I don’t know.

One way to find out what type you are, assuming you’re qualified to be a donor, is to donate blood. They’ll type it and let you know when they send you your donor card. That’s how I know mine (A+).

Yes, it’s probably in your medical records. Some people may have found out in other ways. For example, I always remember that I have type B, because I had to do the “stab yourself in the finger and test your blood type” experiment in HS biology. (Not an easy thing for a needle-phobic person to do.)