英国纽卡斯尔大学生理学.pptVIP

* Physiology PSC1001 Lecture 3 Blood Dr Chris Baldwin christopher.baldwin@ncl.ac.uk Blood groups By the end of this session you should be familiar with 1. The physiological principles of blood groups 2. The ABO System 3. The Rh Group 4. Appreciate the clinical relevance of ABO and Rh Blood Groups 5. Other Blood Groups Blood Groups A complex mixture of glycoproteins and glycolipids are found on the surface of red blood cells. Thus if an individual is exposed to molecules that are not on ‘self’ RBC they will have the capacity to mount an immune response to the ‘foreign’, glycolipids and proteins. The expression pattern of these molecules varies between individuals. A molecule that can induce an immune response is termed an antigen and thus these molecules are termed red blood cell surface antigens. There are 30 human blood group systems and over 600 different blood group antigens have been described. An complete blood group is described as the set of 29 RBC surface antigens of the surface of an individuals RBC. Usually only the ABO blood group system and the presence or absence of Rhesus D antigen (Rhesus factor) are determined to describe blood type. Blood Groups Blood groups are inherited and represent contributions from both parents. The ABO System The ABO system is controlled by the genes A, B, H and h. H is dominant and codes for a fucosyl transferase enzyme that converts a precursor substance in RBCs to H Substance (H substance is a glycoprotein). Therefore HH individuals make H substance Hh individuals make H substance hh individuals do NOT make H substance hh (Oh) individuals These individuals are described as having the Bombay phenotype. Note: They are very rare in the population (1/250 0000) except in parts of India (1/8000). These individuals may posses the A or B gene but as no precursor substance H is made they will not have any ABO antigens. There is no ill effect but people with this blood grou