Explaining malaria protection in blood type O

Scientists from Sweden’s Karolinska Institutet have explained the mysterious mechanism which protects people with blood type O from dying of severe malaria. Their results have been published in the journal Nature Medicine.

Malaria is caused by different kinds of parasites from the plasmodium family, with cases of severe or fatal malaria coming from the species known as Plasmodium falciparum. In severe cases of the disease, the infected red blood cells adhere excessively in the microvasculature and block the blood flow, causing oxygen deficiency and tissue damage that can lead to coma, brain damage and, eventually, death - an outcome which is prevented in people with blood type O.

The Swedish researchers used data from different experiments on cell cultures and animals to show how the P. falciparum parasite secretes RIFIN - a protein which makes its way to the surface of the blood cell, where it acts like glue. The protein was found to bond strongly with the surface of type A blood cells, but only weakly to type O.

Principal investigator Professor Mats Wahlgren explained that since RIFIN is found in many different variants, it has taken the research team a lot of time to isolate exactly which variant is responsible for this mechanism. However, once they were able to tie together previous findings, they came up with a result which was “conceptually simple”.

“We can explain the mechanism behind the protection that blood group O provides against severe malaria, which can, in turn, explain why the blood type is so common in the areas where malaria is common,” Professor Wahlgren said. “In Nigeria, for instance, more than half of the population belongs to blood group O, which protects against malaria.”

Source