"Doctor, why can he transfuse blood type A directly, and I am also type A, why can't I transfuse it directly?"
"Even though you both have type A, you have irregular antibodies in your blood that need to be screened further to find a match."
……
What are irregular antibodies in the blood? Why screen for irregular antibodies? How did it come about? The article of Changde First Hospital of Traditional Chinese Medicine will take you to understand "irregular antibodies".
What is an irregular antibody?
In daily life, we often hear about ABO blood type, as well as the favorite bridge used in film and television dramas - "panda blood", that is, RhD-negative blood.
In fact, the blood group of human red blood cells is very complex, and there are hundreds of blood group antigens found at present, and more than a dozen are often of clinical concern. In addition to the most common and well-known ABO blood group system, there are many other blood group systems such as MNSs, P, Kidd, Duffy, Kell, etc.
There are two types of red blood cell blood group antibodies: regular and irregular, in which the production of ABO blood group system antibodies conforms to Landsteiner's rule, and antibodies that do not target their own red blood cell A or (and) B antigens appear regularly in the blood; The production of antibodies to other blood group systems does not conform to Landsteiner's rule and is called irregular antibodies or accidental antibodies.
To put it simply, irregular antibodies refer to the general term for red blood cell antibodies other than anti-A and anti-B antibodies, also known as accidental antibodies. There are two types of accidental antibodies: alloantibodies and autoantibodies.
How are irregular antibodies created?
The human body has a complete immune mechanism for growth, development and survival, and when stimulated by some exogenous "foreign bodies", it will produce corresponding antibodies.
There are four common types of irregular antibody production pathways.
The first type of pathway is "naturally generated", that is, some people are exposed to the stimuli of certain substances present in the natural environment during growth and development, which have an antigenic structure similar to that of red blood cells, and then produce irregular antibodies, such as pollen, bacteria, etc.
The second pathway is "immune production", which is produced by stimulation of different antigens of foreign red blood cells, such as blood transfusions, organ transplants, or pregnancy.
When the autoimmune tolerance mechanism changes, the body regards its own tissues and components as "foreign bodies", and autoimmune reactions occur to produce antibodies against its own tissues and components.
The fourth category is the antibodies produced by other routes in addition to the above three types of routes, such as antibodies passively obtained by injection of immunoglobulin.
Why screen for irregular antibodies?
Because irregular antibodies can cause transfusion reactions, mild cases cause chills and fever, affecting the treatment effect, and severe cases destroy the transfused uncooperative red blood cells or shorten their lifespan, resulting in hemolytic transfusion reactions, which endanger the patient's life.
Therefore, for patients who require transfusion therapy, irregular antibody screening can help blood selection, prevent hemolytic transfusion reactions caused by transfusion of blood containing the corresponding antigen of a certain antibody, and ensure the safety of blood transfusion.
In addition, for pregnant women, irregular antibodies can cause neonatal hemolytic disease, affect the development of neonatal organs, and in severe cases, endanger the life of newborns. Therefore, pregnant women should also be screened for irregular antibodies, and irregular antibodies can be detected as soon as possible, so that the prevention and treatment of neonatal hemolytic disease can be carried out during pregnancy to reduce the harm to the fetus or newborn.
Is there an irregular antibody positive transfusion?
Hemolytic transfusion reaction occurs when an irregular antibody is positive and red blood cells with the corresponding antigen are transfused.
Therefore, patients need to be screened for irregular antibodies before blood transfusion, and once positive, further antibody identification is required to determine their specificity, and then red blood cells are screened for transfusion without corresponding antigens.
Source: Changde First Hospital of Traditional Chinese Medicine
Editor: Yi Sainan