評(píng)論
打印
【背景】
血型分類:
一般常見A、B、AB和O四種，另外還有RH、MNS、P等極為稀少的10余種血型系統(tǒng)。其中，AB型可以接受任何血型的血液輸入，因此被稱作萬能受血者，O型可以輸出給任何血型的人體內(nèi)，因此被稱作萬能輸血者、異能血者、實(shí)際上，不同血型之間的輸送，一般只能小量的輸送，不能大量。要大量輸血的話，最好還是相同血型之間為好。
狹義地講，血型專指紅細(xì)胞抗原在個(gè)體間的差異；但現(xiàn)已知道除紅細(xì)胞外，在白細(xì)胞、血小板乃至某些血漿蛋白，個(gè)體之間也存在著抗原差異。因此，廣義的血型應(yīng)包括血液各成分的抗原在個(gè)體間出現(xiàn)的差異。通常人們對(duì)血型的了解往往僅局限于ABO血型以及輸血問題等方面，實(shí)際上，血型在人類學(xué)、遺傳學(xué)、法醫(yī)學(xué)、臨床醫(yī)學(xué)等學(xué)科都有廣泛的實(shí)用價(jià)值，因此具有著重要的理論和實(shí)踐意義，同時(shí)，動(dòng)物血型的發(fā)現(xiàn)也為血型研究提供了新的問題和研究方向。
【原文】
Yael: I just read about an exciting technique. Researchers found a way to convert types A and B blood into type O blood--the type that can be transfused into any patient. This advance could help avoid blood shortages in the future.
Don: Wow, that is exciting. But what makes type O blood so special?
Y: Blood types result from different carbohydrates, called antigens(抗原), on the surface of human blood cells. Your blood "type" denotes the kinds of antigens you have on the surface of your cells. People with type A blood have A antigens; those with type B have B antigens. If you have both kinds of antigens, you're type AB; if you have neither one, you're type O.
Your immune system recognizes the antigens on your blood as "self", but attack cells with "foreign" antigens. So if you ever need a blood transfusion, it's important that you only receive blood compatible with your own type.
D: I see. So if a type A person receives type B or AB blood, her immune system will see the B-antigens as foreign, and attack the donor blood cells?
Y: Exactly. But type O is called the "universal donor" since it doesn't have any antigens that would set off the body's defense system.
A team of Danish scientists has identified enzymes that remove the A and B antigens from blood cells. The enzymes, which were extracted from a bacteria and a fungus, essentially change any donated blood into type O.
Clinical trials are underway to test whether the treated blood is safe and effective. If so, the technology could help save lives, since type O blood is such a precious commodity.
