Viewing a single comment thread. View all comments

Greyswandir t1_j47il1a wrote

Reply to comment by OnlyCuntsSayCunt in Is there physical differences between blood types? by terrip_t1

Very tiny. A blood cell is around 7-8um across (there are 1000 um, micrometers or microns, in every millimeter). A surface protein is probably around the 10s of nm (nanometers, there are 1000 nm in every um) large. So roughly a thousand times smaller.

It is relatively easy to see cells with a microscope. With a light microscope you generally cannot see proteins because they are too small. Microscopes are limited by something called the diffraction limit, which is usually around 0.25um (or 250nm).

However you can see much smaller structures with an electron microscope and could presumably “see” surface proteins in that manner.

You could also use a stain or dye which colors the cell based on what surface proteins are present. You wouldn’t directly see the proteins, but you could differentiate blood type based on an indirect visualization (the color)

28

coilycat t1_j47oo3z wrote

wait, the color of the entire cell would change based on the surface protein?

4

Greyswandir t1_j4805j5 wrote

Depending on how you dye/stain the cell, yes. The surface proteins are distributed all across the surface. So if you use a dye which only sticks to those proteins it would color the whole surface of the cell.

There are ways of binding dyes to targeting moeties, like antibodies, that only stick to one type of target. So you could theoretically make different batches with different colors of dyes and bind them to different targeting moeties so only blood cells with that group get stained that color.

There are way, way, way easier and more practical ways to type blood though. So I don’t know that anyone would actually go through the work to do this or what it would accomplish. Just saying this is a way to achieve what the OP asked about and actually see a clear difference under the microscope.

12

Norwester77 t1_j47xj2p wrote

If you add a dye of a particular color that sticks to the particular surface protein, yes.

6

terrip_t1 OP t1_j493lp9 wrote

Thank you for explaining this so well

2

DifferentCard2752 t1_j49v1qa wrote

Would you be willing explain the other, rare blood types? For example a family member has the Kidd blood type) Found out the 8 blood types are just the most common, and there’s actually a bunch more.

2

Greyswandir t1_j4a1950 wrote

Sure, but I’m not an expert by any stretch of the imagination. So the cell is surrounded by a membrane. That membrane is absolutely covered in tons and tons and tons of proteins which stick out above the surface of the membrane. We call these surface proteins because they extend above the surface. Those proteins can be used to mark what type of cell the cell is, interact with chemicals floating around outside the cell, bind the cell to various structural components or other cells etc. These are sometimes called surface antigens, because antibodies can be bind to them.

The normal blood group markers, the ABO system, represent a set of surface antigens. The ABO and Rh (that’s the +/- part) happen to be particularly important to how the body recognizes self vs foreign cells. So it’s really important to match those correctly.

But the blood cells have hundreds of different antigens. And just because the ABO and Rh groups are particularly important for recognition doesn’t mean those other antigens aren’t also used. And to make it even more complicated, different people seem to respond more or less strongly to different groups (although ABO seems to be close to universally important)

Here’s an article I found on the topic

5

Minute_Farmer t1_j4cz2j8 wrote

The only other one I know anything about is the Bombay Phenotype, which is when you have blood cells that have no antigens on them at all. Even O- has the base receptors that all blood cells have (H antigen) but if you have Bombay Phenotype then you don't have those either. Idk what medical issues this causes but it definitely makes it extremely hard if not impossible to get blood if you need it because you would have to get blood from someone else with that rare mutation: there is no other alternative.

2

lallen t1_j4dw2a5 wrote

Duff, Kelly and Kidd are the most clinically significant after AB0 and Rh. They are not generally reported in blood typing blood tests, instead a "screening" is performed. Here a general test of the presence of the most common antibodies in the patient's blood is done (so not the antigens on the blood cells).

In addition, you can do a "cross match" where donor blood is exposed to patient plasma to check for incompatibility

2

fleur_essence t1_j4g2v4w wrote

Kidd antigens: A red cell has a ton of molecules on the cell surface that helps it do what a cell gotta do. One such molecule is an ion transporter (helps urea travel from one side of the cell membrane to the other. Almost all people have this protein, but at some point there was a mutation, so about 50% of people have “version a” while about 50% of people have “version b” and another 25% have both “Jka” and “Jkb”. These are the main Kidd antigens (Jka and Jkb are abbreviations). So, really there’s nothing special about having a Kidd antigen on your red cell. The problem happens if you’re missing one (ie type Jkb only) and get exposed to some blood from a Jka person. There’s a chance your immune system notices the difference and forms anti-Jka antibodies. Once the hospital knows you have formed this antibody, they’ll do their best to give you Jka-negative blood to prevent the transfusion from being destroyed by your immune system.

Just as an aside, there are tons of different blood group system (types of molecules on the red blood cell surface that can vary between one person and another). It’s impractical to “match” a blood unit up front to each persons molecules except for the ABO and Rh+/- everyone’s talked about. So we only special-select blood if there’s a known antibody, with the exception of sickle cell patients.

2