22.26
Grupo sanguíneo Rh
El antígeno Rhesus (Rh) es crucial para determinar los grupos sanguíneos y garantizar la compatibilidad durante las transfusiones de sangre.
El antíge…
El antígeno Rhesus o Rh es una clase de aglutinógeno en los glóbulos rojos o glóbulos rojos. Su presencia o ausencia categoriza a una persona como Rh positivo o Rh negativo.
Al informar sobre el grupo sanguíneo de una persona, el antígeno Rh generalmente se combina con los antígenos A y B.
Por ejemplo, el tipo de sangre de una persona con los antígenos A y Rh se designa como A-positivo. Por el contrario, en ausencia de antígeno Rh, la sangre de la persona se denomina A-negativa.
A diferencia del sistema ABO, el plasma no contiene naturalmente anticuerpos anti-Rh.
Por lo tanto, la exposición al antígeno Rh puede desencadenar una respuesta inmunitaria en los individuos Rh negativos, lo que conduce a la hemólisis.
Por ejemplo, supongamos que una madre Rh negativa lleva un feto Rh positivo. En ese caso, el sistema inmunitario de la madre reconoce el antígeno Rh de los glóbulos rojos fetales como extraño, lo que desencadena la producción de anticuerpos anti-Rh.
Por lo general, estos anticuerpos no interfieren en el primer embarazo. Sin embargo, en embarazos posteriores con fetos Rh positivos, los glóbulos rojos fetales corren el riesgo de hemólisis debido a los anticuerpos anti-Rh existentes en la sangre de la madre.
View the full transcript and gain access to JoVE Core videos
Q1: What is the Rh antigen and how does it determine blood type?
The Rh antigen is a protein on red blood cell surfaces that classifies blood as Rh-positive or Rh-negative. Its presence or absence is combined with ABO antigens to designate complete blood types, such as A-positive or B-negative. Understanding the Rh factor is essential in transfusion medicine for ensuring blood compatibility.
Q2: Why don't Rh-negative people naturally have anti-Rh antibodies?
Unlike the ABO system, plasma does not naturally contain anti-Rh antibodies. Anti-Rh antibodies develop only after exposure to the Rh antigen, triggering an immune response in Rh-negative individuals. This delayed response is why first transfusions with incompatible Rh blood may not cause immediate problems, but subsequent exposures carry greater risk.
Q3: How does Rh incompatibility affect pregnancy and the fetus?
When an Rh-negative mother carries an Rh-positive fetus, her immune system may recognize fetal Rh antigens as foreign, producing anti-Rh antibodies. In the first pregnancy, these antibodies typically cause no harm. However, in subsequent pregnancies with Rh-positive fetuses, existing antibodies cross the placenta and attack fetal red blood cells, causing hemolysis and hemolytic disease of the newborn.
Q4: What is RhoGAM and how does it prevent hemolytic disease of the newborn?
RhoGAM is a serum containing anti-Rh antibodies administered to Rh-negative mothers during and after delivery of Rh-positive babies. It prevents the mother's immune system from recognizing fetal Rh antigens as foreign, stopping anti-Rh antibody production. This protective measure significantly reduces the risk of hemolytic disease in future pregnancies.
Q5: How is the Rh blood group reported alongside the ABO system?
The Rh antigen status is combined with ABO antigens when reporting blood type. A person with A and Rh antigens is designated A-positive, while someone with A antigens but no Rh antigen is A-negative. This combined classification ensures accurate blood matching for transfusions and identifies potential maternal-fetal incompatibility risks.
Q6: What happens when Rh-negative individuals receive Rh-positive blood?
Exposure to Rh-positive blood triggers an immune response in Rh-negative individuals, leading to anti-Rh antibody production. This can cause hemolysis, the destruction of red blood cells, resulting in transfusion complications. Subsequent transfusions with Rh-positive blood carry increased risk of severe hemolytic reactions due to existing antibodies.
Q7: Why is understanding Rh compatibility critical in transfusion medicine?
Incompatible Rh factors between donor and recipient trigger immune responses causing hemolysis and potential life-threatening complications. Proper Rh typing prevents transfusion reactions and is especially vital for Rh-negative recipients who lack natural anti-Rh antibodies. Accurate Rh classification ensures safe blood matching and protects patient health during transfusions.