All Blood Tests

Researchers in England dug up the bodies of people who’d died from the 1665 London plague, and made the startling discovery that most of the people who died had type B blood, and that far fewer people have type B blood now than before the plague. Scientist now must explain why people

with Type B blood were more likely to die from plague.

When a germ gets into your system, you make a protein

called an antibody that attaches to it and kills it. Your body

is never supposed to make antibodies against itself. Your

immunity recognizes a germ by the sugar surfaces on cell

membranes. Type B surface membrane on red cells is the

same as the surface membrane of certain bacteria, including

Yersinia pestis, the flea-borne bacteria that caused the plague.

If you are type B, you cannot make antibodies against type B

surface of cells, because you would destroy all your red blood

cells. If yersinia gets into your bloodstream, your immunity does

not kill it, so it causes blisters and swollen lymph nodes, and

you can go into shock and die.

People in blood group A are at higher risk for heart

attacks than those in other groups because their blood is far

more likely to clot. They have higher blood levels of factor VIII,

which helps blood clot, and clots are the terminal factor that

blocks arteries to cause a heart attack. There are more than

300 known variations in blood types, and researchers are still

learning about their effects.