Your guide to the varieties of delicious, nutritious human blood
Or: what do blood types actually mean? Also: an offer, with a free signed book? My God.
First, a reminder that the improved and updated edition of The Compendium of (Not Quite) Everything will be available in the shops in under three weeks. If you want a copy TOUCHED BY MY VERY OWN HANDS – that is, one I’ve signed and dedicated to the reader of your choice – you can order one from Backstory here.
Anyway, some actual writing: this went to paying subscribers in March.
I gave blood for the first time a few weeks ago. I’d been meaning to do this for years, but life and events and a fundamental if guilt-ridden selfishness had all got in the way. This time, though, when Londoncentric’s Jim Waterson mentioned on Bluesky that there was a severe shortage of blood, I reached for my usual stock of excuses, realised I didn’t have one and actually did it. I’m glad.
Some brief observations of the process itself. It is deeply weird but not entirely unpleasant to be in a comfy position, knowing that your blood is draining from your body. It is unnerving and amusing in equal measure that, once it has enough of your vital fluids, the machine makes a noise like a fruit machine. Afterwards I felt lovely and floaty, like I had just taken some really good painkillers and then had a small G&T, and spent ten minutes in the Stratford Westfield branch of Foyles marvelling at the sheer existence of books. To get there, though, I did first have to convince a nurse that the kind of lightheaded I was feeling was the good, “nicely stoned” kind, not the bad “danger to myself and others” kind.
On the whole, ten out of ten donor experience. Would donate again. Actually: will donate again, this very week, as it happens.
Another reason I wanted to do it is because I’d always wondered what my blood type was and this seemed one of the least medically unpleasant ways of finding out. And true to form, two days later, the NHS sent me an email congratulating me on being A+, the second most common blood type, possessed by roughly 30% of the population. Brilliant!1
Once I was in possession of this information, and had had enough time to ponder how I felt about having a blood type described as “common” and then conclude that this was a stupid thing to worry about, I realised: I have absolutely no idea what it means. What follows is my attempt to find out.
Your blood type, it turns out, is essentially about which substances your immune system is minded to view as foreign bodies. There are two types of antigens – A and B – which can be present on your red cells. If there is a type you don’t have, you will have the opposite antibodies in your blood plasma, ready to attack any interlopers.
That gives us our four major blood groups:
A (red cells have A antigens; antibodies will attack those with B antigens);
B (red cells have B antigens; antibodies will attack those with A antigens);
AB (red cells have both; antibodies will attack neither);
O (red cells have neither; antibodies will attack both).
What about being positive or negative? That’s a reference to the presence (+) or absence (-) of Rhesus (Rh) protein, named for the monkeys because of their involvement in the studies that helped identified it, and which provide another complicating factor in who can donate to whom.
In other words, there are three things – A antigens, B antigens or Rh proteins – which could trigger an immune response in someone whose system is not used to them. O- – your basic blood, with no fancy features – is the universal donor because there’s nothing in it that’s going to offend anybody. It’s a bugger if you’re in the 13% of the population with O- blood and need a transfusion, though, as your system is going to get sniffy about almost anything. I’m not going to list the symptoms that could result, merely note that they are described as “a serious and potentially fatal immune response”, and leave things there. Getting an incompatible blood transfusion is not a good thing.
At the other end of the spectrum, there’s AB+, which has all three of those complicating factors. If you’re AB+, you can receive blood of any type, and your system will accept it (”the universal recipient”). You can only donate to other AB+ people, though, as everyone else’s system is going to go nuts.
Which blood type you get is a matter of genetics, which means that the relative distribution of blood types varies around the world. Generally speaking, though, you’re more likely to have the RH protein than not to (so more of us are positive than negative), and O is the most common blood group, followed by A, B and AB. Put it all together, and O+ is relatively common; AB- extremely rare.
Here, courtesy of the NHS, are rough figures for the UK, dating from 2018:
O positive: 35%
O negative: 13%
A positive: 30%
A negative: 8%
B positive: 8%
B negative: 2%
AB positive: 2%
AB negative: 1%
There are over 40 other blood group systems, based on the presence of other proteins or antigens. The reason we don’t tend to hear about them quite so often is that they have a much lower risk of causing complications. A life-threatening lack of blood is therefore riskier than providing slightly the wrong flavour of it, so it’s relatively rare to test for them.
Pregnant women, though, often are screened for the presence of Kell antigens (named for Mrs Kellacher, the first patient found to have them), as well as receiving more detailed RH screening, to ensure they’re not receiving a type of blood that can damage the baby. In rare cases, the blood types of mother and baby can be so incompatible that it can result in miscarriage. The treatment to prevent that involves injections of antibodies present in extremely rare types of blood.
Which is why it was that James Harrison, an otherwise unremarkable Australian who died in his sleep last February at the age of 88, received multiple obituaries on the other side of the world. In 1951, aged 14, Harrison underwent surgery that required blood transfusions. He vowed to repay the favour once an adult by donating his own blood, and soon learned that his plasma contained unusually strong examples of those very antibodies. He gave blood every fortnight for over 60 years, 1,173 donations in total, and only stopped because of a legal bar on those aged over 81 doing so.
His blood is estimated to have saved 2.4 million babies. He was also scared of needles.
The above is *not* an extract from The Compendium of (Not Quite) Everything, but the book is nonetheless a compilation of exactly that sort of thing. Here’s the blurb…
“…a treasure trove of random knowledge. Covering everything from the furthest known galaxies to the murky origins of oyster ice cream, inside you will find a discussion of how one might determine the most average-sized country in the world; details of humanity's most ridiculous wars; and, at last, the answer to who would win in a fight between Harry Potter and Spider-Man.”
If that sounds like your thing, and you fancy a signed copy, you can get one from South London’s finest bookshop Backstory here. In fact, what the hell, sign up here, and I’ll send you a free one with an annual subscription to this very newsletter.
The NHS Blood Donation service actually texted me, several times, before I donated telling me they were desperately short of my blood type. Since neither they nor I knew what my blood type was, this felt like an insight into both the current shortage of blood, and the current shortage of non-manipulative promotional messages.