Abosystem: a classification system for human blood that identifies four major blood types based on the presence or absence of two antigens a and bon red blood cells.
abo血型分类法：一种人类血型分类方法，以红细胞上有无a和b两种抗原而分为四种血型。
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As last year, the day will be celebrated on 14 June, the birth date of Karl Landsteiner, who discovered the ABO blood group system.