Immune hematology(abo)
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Immune hematology(abo)

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Immune hematology(abo) Immune hematology(abo) Presentation Transcript

  • Immune hematology(ABO) Eman youssif
  • Introduction: The Kell blood group system is complex and contains many antigens that are highly immunogenic. These antigens are the third most potent, after those of the ABO and Rh blood groups, at triggering an immune reaction. Antibodies that target Kell antigens can cause transfusion reactions and hemolytic disease of the newborn (HDN). In the case of HDN, ABO and Rh incompatibility are more common causes. However, disease caused by maternal anti-ABO tends to be mild, and disease caused by maternal anti-Rh can largely be prevented. The infrequent cases of HDN caused by Kell immunization tend to result in severe fetal anemia because maternal anti-Kell target fetal red blood cell (RBC) precursors, suppressing the fetal production of RBCs.
  • Difference Between Blood Types O+ and O- blood group O is the blood group that has neither antigen A nor antigen B, which is present in blood types A and B respectively. As far as the Rhesus factor is concerned, a person is said to be Rhesus positive if he has the D antigen present on the surface of his red blood cells. If the D antigen is absent, then the person is said to be Rhesus negative. So, a person who is O positive does not have antigen A nor antigen B, but has D antigen present on the surface of his red blood cells. On the other hand, a person who is O negative, has neither antigen A or B, nor antigen D present on the surface of his red blood cells. Read more at Buzzle: http://www.buzzle.com/articles/what- is-the-difference-between-blood-types-opositive-and- onegative.html
  • One of the main purpose of knowing your blood type is that it can help you determine which blood types you can receive blood from in case of an emergency where you need blood. Since O+ does not have antigen A nor B, it cannot receive blood from either blood types A nor B, irrespective of their Rhesus factors. However, they can receive blood from O+ people and also from O- people. While O- people do not have the D antigen, they don't have anti-D antigens either, and therefore they do not agglutinate when they come in contact with O blood type cells that have D antigen. O- patients however, can receive blood only from people who have O- blood type. If any other blood type is introduced into the body of a person who has O- blood type it can result in transfusion reaction. The bottom line therefore is that people with blood type O positive can receive blood from people with O positive as well O negative blood type, but O negative people can only receive blood from someone with O negative blood type. Read more at Buzzle: http://www.buzzle.com/articles/what-is-the-difference- between-blood-types-opositive-and-onegative.html
  • People who have O positive blood type can donate blood to all blood types who have a positive Rhesus factor, as the surface of O blood cells do not have any antigens, i.e. antigen A nor B, and that rules out the chances of blood transfusion reaction. Blood type O negative can donate blood to every blood type, irrespective of the ABO group or the Rhesus group present, this blood type is not known to react with any of the blood types. Simply put, people with blood type O+ can donate blood to A+, B+, AB+ and O+ people, while people with blood type O-, which is often referred to as the universal donor, can donate blood to people with any blood type. Read more at Buzzle: http://www.buzzle.com/articles/what-is-the-difference-between-blood- types-opositive-and-onegative.html
  • Fetal-Maternal Hemorrhage and Stillbirth Fetal-maternal hemorrhage (FMH) has been of considerable interest and importance to obstetricians for decades: leakage of fetal cells into the maternal circulation is the mechanism through which Rh sensitization arises. In addition, more recent data have shown that when large volumes of fetal blood are lost in this way, then serious and potentially fatal fetal or neonatal outcomes can result. The Wisconsin Stillbirth Service Program to this point has not recommended routine assessment for FMH as a possible cause of stillbirth. Literature review was undertaken in order to determine if this policy should be changed. Leakage of fetal red blood cells can begin anytime from the mid-first trimester onward. It presumably results from a breach in the integrity of the placental circulation. As pregnancy continues, more and more women will show evidence of fetal red cells in their circulation so that by term about 50% will have detectable fetal cells. Most of these, however, are very small leaks; total fetal blood volume lost in this way is 2 milliliters or less in 96-98% of pregnancies.
  • The Kleihauer–Betke ("KB") test, Kleihauer–Betke ("KB") stain or Kleihauer test, is a blood test used to measure the amount of fetal hemoglobin transferred from a fetus to a mother's bloodstream.It is usually performed on Rhesus-negative mothers to determine the required dose of Rho(D) immune globulin (RhIg) to inhibit formation of Rh antibodies in the mother and prevent Rh disease in future Rh-positive children.
  • Fetal–maternal hemorrhage severity estimation To determine if a positive test for FMH should be considered as the likely cause of fetal death, the percent of total fetal blood volume lost should be calculated, making appropriate adjustments based on the following known relationships:
  • the size of a fetal red blood cell is 1.22 times that of an adult red blood cell; the KB stain is known to have a mean success rate of 92% in detecting fetal red blood cells; in a woman at or near term in her pregnancy, the mean volume of maternal red blood cells is approximately 1800 ml; the mean fetal hematocrit is 50%; and at stillbirth, the mean fetal blood volume is 150 frac{ml}{kg} These constraints can then be applied to yield the formula PFB = frac{(3200)(FC)}{(FW)(MC)}
  • where PFB is the percentage of fetal blood lost; FC is the observed number of fetal red blood cells; MC is the observed number of maternal red blood cells (N.B. we have that MC = TC - FC, where TC is the total observed number of red blood cells, both maternal and fetal); FW is the stillbirth weight of the fetus in kilograms.
  • Part2:Anti-D (Rho) Immunoglobulin The development of anti-D antibodies generally results from feto-maternal haemorrhage (FMH) occurring in rhesus D (RhD) negative women who carry an RhD positive fetus. In later pregnancies, anti-D antibodies can cross the placenta, causing worsening rhesus haemolytic disease with each successive rhesus positive pregnancy.
  • References: http://www.transfusion.com.au/dise ase_therapeutics/pregnancy/guidelin Ig-RhD-es