Karl Landsteiner (lahir 14 Juni 1868 – meninggal 26 Juni 1943 pada umur 75 tahun) ialah seorang ilmuwan Austria keturunan Yahudi. Ialah tokoh yang menemukan bahwa darah manusia terbagi menjadi 4 kelompok yang sekarang dikenal dengan golongan darah O, A, B, dan AB. Dengan penemuannya tersebut, orang dapat mentransfusi darahnya dengan aman dan tidak sembarangan untuk menstrafusi darah. Ilmuwan Austria, Karl Landsteiner, memperoleh penghargaan Nobel dalam bidang Fisiologi dan Kedokteran pada tahun 1930 untuk jasanya menemukan cara penggolongan darah ABO. Jan Janskýdi pada tahun 1907 mengklasifikasikan darah manusia ke dalam empat grup, yang hingga kini masih digunakan.Golongan darah adalah ilmu pengklasifikasian darah dari suatu kelompok berdasarkan ada atau tidak adanya zat antigen warisan pada permukaan membran sel darah merah. Hal ini disebabkan karena adanya perbedaan jenis karbohidrat dan protein pada permukaan membran sel darah merah tersebut. Dua jenis penggolongan darah yang paling penting adalah penggolongan ABO dan Rhensus (faktor Rh). Di dunia ini sebenarnya dikenal sekitar 46 jenis antigen selain antigen ABO dan Rh, hanya saja lebih jarang dijumpai. Transfusi darah dari golongan yang tidak kompatibel dapat menyebabkan reaksi transfusi imunologis yang berakibat anemia hemolisis, gagal ginjal, syok, dan kematian.
Secara umum, golongan darah O adalah yang paling umum dijumpai di dunia, meskipun di beberapa negara seperti Swedia dan Norwegia, golongan darah A lebih dominan. Antigen A lebih umum dijumpai dibanding antigen B. Karena golongan darah AB memerlukan keberadaan dua antigen, A dan B, golongan darah ini adalah jenis yang paling jarang dijumpai di dunia. Jenis penggolongan darah lain yang cukup dikenal adalah dengan memanfaatkan faktor Rhesus atau faktor Rh. Nama ini diperoleh dari monyet jenis Rhesus yang diketahui memiliki faktor ini pada tahun 1940 oleh Karl Landsteiner. Seseorang yang tidak memiliki faktor Rh di permukaan sel darah merahnya memiliki golongan darah Rh-.
Mereka yang memiliki faktor Rh pada permukaan sel darah merahnya disebut memiliki golongan darah Rh+. Jenis penggolongan ini seringkali digabungkan dengan penggolongan ABO. Golongan darah O+ adalah yang paling umum dijumpai, meskipun pada daerah tertentu golongan A lebih dominan, dan ada pula beberapa daerah dengan 80% populasi dengan golongan darah B. Kecocokan faktor Rhesus amat penting karena ketidakcocokan golongan. Misalnya donor dengan Rh+ sedangkan resipiennya Rh-) dapat menyebabkan produksi antibodi terhadap antigen Rh(D) yang mengakibatkan hemolisis. Hal ini terutama terjadi pada perempuan yang pada atau di bawah usia melahirkan karena faktor Rh dapat memengaruhi janin pada saat kehamilan.
Karl Landsteiner, ForMemRS (June 14, 1868 – June 26, 1943), was an Austrian and American biologist and physician. He is noted for having first distinguished the main blood groups in 1900 (however, Jan Janský described and distinguished main blood groups before him), having developed the modern system of classification of blood groups from his identification of the presence of agglutinins in the blood, and having identified, with Alexander S. Wiener, the Rhesus factor, in 1937, thus enabling physicians to transfuse blood without endangering the patient′s life. With Constantin Levaditi and Erwin Popper, he discovered the polio virus in 1909. He received the Aronson Prize in 1926. In 1930 he received the Nobel Prize in Physiology or Medicine. He was awarded a Lasker Award in 1946 posthumously and is recognized as the father of transfusion medicine.Landsteiner’s father, Leopold (1818–1875), a renowned Viennese journalist who was editor-in-chief of Die Presse, died at age 56, when Karl was only 6. This led to a close relationship between Landsteiner and his mother Fanny (née Hess; 1837–1908). After graduating with the Matura exam from a Vienna secondary school, he took up the study of medicine at the University of Vienna and wrote his doctoral thesis in 1891. While still a student he published an essay on the influence of diets on the composition of blood. From 1891 to 1893, Landsteiner studied chemistry in Würzburg under Hermann Emil Fischer, in München under Eugen Bamberger and in Zürich under Arthur Rudolf Hantzsch. A number of publications from that period, some of them in co-operation with his professors, show that he did not restrict himself to hearing lectures.
Landsteiner had to endure continual hardships in Europe until he was invited to accept a position at the Rockefeller Institute of Medical Research in the United States in 1922. In 1900 Karl Landsteiner found out that the blood of two people under contact agglutinates, and in 1901 he found that this effect was due to contact of blood with blood serum. As a result, he succeeded in identifying the three blood groups A, B and O, which he labelled C, of human blood. Landsteiner also found out that blood transfusion between persons with the same blood group did not lead to the destruction of blood cells, whereas this occurred between persons of different blood groups. Based on his findings, in 1907 the first successful blood transfusion was performed by Reuben Ottenberg at Mount Sinai Hospital in New York.
Today it is well known that persons with blood group AB can accept donations of the other blood groups, and that persons with blood group O can donate to all other groups. Individuals with blood group AB are referred to as universal recipients and those with blood group O are known as universal donors. These donor-recipient relationships arise due to the fact that persons with AB do not form antibodies against either blood group A or B. Further, because type O blood possesses neither characteristic A nor B, the immune systems of persons with blood group AB do not refuse the donation. In today’s blood transfusions only concentrates of red blood cells without serum are transmitted, which is of great importance in surgical practice. In 1930 Landsteiner was awarded the Nobel Prize in Physiology or Medicine in recognition of these achievements. For his pioneering work, he is recognized as the father of transfusion medicine.
