Blood Type-Dis­ease Link Ex­plained

Health & Nutrition - - FLASH -

Doc­tors first be­gan to no­tice a con­nec­tion be­tween blood types and dif­fer­ent dis­eases in the mid­dle of the 20th Cen­tury, and the list has con­tin­ued to grow. They no­ticed for ex­am­ple that peo­ple with blood type A are at a higher risk of cer­tain types of can­cer, such as pan­cre­atic can­cer and leukaemia, small­pox in­fec­tions, heart dis­ease and se­vere malaria. On the other hand re­searchers at the Uni­ver­sity of Toronto peo­ple with type O are bet­ter pro­tected against se­vere malaria but are more likely to get ul­cers and rup­tured Achilles ten­dons. Th­ese links be­tween blood types and dis­eases have a cer­tain ar­bi­trari­ness about them, and sci­en­tists have only be­gun to work out the rea­sons be­hind some of them. Their stud­ies in­di­cate that the pro­tec­tion oc­curred be­cause im­mune cells have an eas­ier job of recog­nis­ing in­fected blood cells if they’re type O rather than other blood types. Take norovirus. This nasty pathogen is the bane of cruise ships, as it can rage through hun­dreds of pas­sen­gers, caus­ing vi­o­lent vom­it­ing and di­ar­rhoea. It does so by in­vad­ing cells lining the in­testines, leav­ing blood cells un­touched. Nev­er­the­less, peo­ple’s blood type in­flu­ences the risk that they will be in­fected by a par­tic­u­lar strain of norovirus. The so­lu­tion to this par­tic­u­lar mys­tery was found in the fact that blood cells are not the only cells to pro­duce blood type anti­gens. They are also pro­duced by cells in blood ves­sel walls, the air­way, skin and hair. Many peo­ple even se­crete blood type anti­gens in their saliva. Noroviruses make us sick by grab­bing onto the blood type anti­gens pro­duced by cells in the gut. Yet a norovirus can only grab firmly onto a cell if its pro­teins fit snugly onto the cell’s blood type anti­gen. So it’s pos­si­ble that each strain of norovirus has pro­teins that are adapted to at­tach tightly to cer­tain blood type anti­gens, but not oth­ers. That would ex­plain, re­searchers the­o­rize, why our blood type can in­flu­ence which norovirus strains can make us sick. Sci­en­tists say this may also be a clue as to why a va­ri­ety of blood types have en­dured for mil­lions of years. Our pri­mate an­ces­tors were locked in a never-end­ing cage match with count­less pathogens, in­clud­ing viruses, bac­te­ria and other enemies. Some of those pathogens may have adapted to ex­ploit dif­fer­ent kinds of blood type anti­gens. The pathogens that were best suited to the most com­mon blood type would have fared best, be­cause they had the most hosts to in­fect. But, grad­u­ally, they may have de­stroyed that ad­van­tage by killing off their hosts. Mean­while, pri­mates with rarer blood types would have thrived, thanks to their pro­tec­tion against some of their enemies.

Newspapers in English

Newspapers from India

© PressReader. All rights reserved.