5 ms·

Long time listener, first time caller (finally made a HN account).. Anyways, can someone please explain how positive/negative plays a factor here? Rh +/- is me

Long time listener, first time caller (finally made a HN account).. Anyways, can someone please explain how positive/negative plays a factor here? Rh +/- is mentioned once in the article but not discussed as far as being a donor. I was always told O- is the universal red cell donor [1]. Can anyone help explain is this enzyme fixes the +/- component in addition to the ABO component? Thanks! [1] https://www.redcrossblood.org/donate-blood/blood-types.html https://www.redcrossblood.org/donate-blood/blood-types.html

Terr_ 2y ago
That's probably a separate and harder problem from this: The A and B antigens refer to the presence of carbohydrates extending from the cell membrane, whereas Rh factor + refers to the presence of a protein. Since there are different classes of bio-molecules, proteins may need different techniques to remove, alter, or cover them up. If we do find such techniques, they may have much broader applications in immunology.
- XorNot 2y ago
  Rhesus factor is a lot more forgiving though: i.e. in a crisis you can transfuse rhesus positive blood to a rhesus negative person successfully since the sensitization doesn't emerge immediately.
HPsquared 2y ago
There are three components that can cause problems with transfusions: "A", "B" and "Rhesus". A person can have any combination of those three (8 combinations). The A/B/AB/O is basically having only A, only B, both, or neither. And the +/- is whether you have the "Rhesus" component. The basic rule is that you can't introduce new components to a person who doesn't have them in their system, and will be treated as foreign contaminants. So someone with all three components already (AB+) can take any blood because their system already is used to all three components. A person with none of the components in their system (O-) would have an allergic reaction to any of the three components being introduced. On the other hand their blood is safe to donate to anyone else as it won't introduce any "unexpected components" to a recipient. EDIT: ah, I see - article doesn't mention Rhesus. I guess it can convert AB- to O-, or AB+ to O+.
- wbl 2y ago
  Oh there are more. I think hundreds are known, but only a few populations have each one.
- smegger001 2y ago
  there is also the HH blood group that will react negatively to O type blood as well as A and B.
  - Terr_ 2y ago
    That naming is a little confusing, because if you say "blood group "A" or "B", that indicates the presence of A and B antigen structures, however "blood group H" means a lack of H. (Since almost everybody has H, it was discovered much later.) Since H is also a building-block needed for A and B to show up, it makes for fun medical-mystery plots, where a child's blood-type seems to be O and doesn't match their parents, but in reality they did get parental A/B/AB genes that just aren't able to express because each parent contributed a nonfunctional H-allele. https://www.ncbi.nlm.nih.gov/books/NBK2268/ https://www.ncbi.nlm.nih.gov/books/NBK2268/
    - Terr_ 2y ago
      P.S. IANAPhlebotomist, but if I could wave a wand to change the nomenclature, I'd make it stop relying on an implicit "nothing" state that keeps changing under us as we discover new features that are either usually-present or usually-absent. Instead patients would have a "blood code" that indicates the tested presence or absence of phenotype cellular features, and any feature not listed would be considered "not yet known, do a test if it might be important." For example, today's AB- would become +HAB-R for "has H,A,B lacks Rhesus factor." Similarly, O+ would become +HR-AB, and the super rare mutation we were just talking about would be either +R-HAB or -HABR. Then when we eventually discover a yet-another factor X... Well, yes, your code wouldn't be constant throughout your life, because after an X-test it would gain either a +X or -X... However the upshot is that it eliminates weird implicit guessing games, and medical professionals will "know what they don't know".

Terr_ 2y ago

That's probably a separate and harder problem from this: The A and B antigens refer to the presence of carbohydrates extending from the cell membrane, whereas Rh factor + refers to the presence of a protein. Since there are different classes of bio-molecules, proteins may need different techniques to remove, alter, or cover them up. If we do find such techniques, they may have much broader applications in immunology.

XorNot 2y ago
Rhesus factor is a lot more forgiving though: i.e. in a crisis you can transfuse rhesus positive blood to a rhesus negative person successfully since the sensitization doesn't emerge immediately.

HPsquared 2y ago

There are three components that can cause problems with transfusions: "A", "B" and "Rhesus". A person can have any combination of those three (8 combinations). The A/B/AB/O is basically having only A, only B, both, or neither. And the +/- is whether you have the "Rhesus" component. The basic rule is that you can't introduce new components to a person who doesn't have them in their system, and will be treated as foreign contaminants. So someone with all three components already (AB+) can take any blood because their system already is used to all three components. A person with none of the components in their system (O-) would have an allergic reaction to any of the three components being introduced. On the other hand their blood is safe to donate to anyone else as it won't introduce any "unexpected components" to a recipient. EDIT: ah, I see - article doesn't mention Rhesus. I guess it can convert AB- to O-, or AB+ to O+.

wbl 2y ago
Oh there are more. I think hundreds are known, but only a few populations have each one.
smegger001 2y ago
there is also the HH blood group that will react negatively to O type blood as well as A and B.
- Terr_ 2y ago
  That naming is a little confusing, because if you say "blood group "A" or "B", that indicates the presence of A and B antigen structures, however "blood group H" means a lack of H. (Since almost everybody has H, it was discovered much later.) Since H is also a building-block needed for A and B to show up, it makes for fun medical-mystery plots, where a child's blood-type seems to be O and doesn't match their parents, but in reality they did get parental A/B/AB genes that just aren't able to express because each parent contributed a nonfunctional H-allele. https://www.ncbi.nlm.nih.gov/books/NBK2268/ https://www.ncbi.nlm.nih.gov/books/NBK2268/
  - Terr_ 2y ago
    P.S. IANAPhlebotomist, but if I could wave a wand to change the nomenclature, I'd make it stop relying on an implicit "nothing" state that keeps changing under us as we discover new features that are either usually-present or usually-absent. Instead patients would have a "blood code" that indicates the tested presence or absence of phenotype cellular features, and any feature not listed would be considered "not yet known, do a test if it might be important." For example, today's AB- would become +HAB-R for "has H,A,B lacks Rhesus factor." Similarly, O+ would become +HR-AB, and the super rare mutation we were just talking about would be either +R-HAB or -HABR. Then when we eventually discover a yet-another factor X... Well, yes, your code wouldn't be constant throughout your life, because after an X-test it would gain either a +X or -X... However the upshot is that it eliminates weird implicit guessing games, and medical professionals will "know what they don't know".