Significance of irregular antibody screening in clinical blood transfusion

Irregular antibodies are also known as red blood cell antibodies. The so-called irregular antibodies are blood type antibodies other than Anti-A and anti-B, most of which are IgG antibodies. It is mainly produced by immune stimulation such as blood transfusion or pregnancy. In saline medium, red blood cells that cannot be aggregated but can only be allergic to the corresponding antigen must pass through special media (enzymes, anti-human globulin, polybrene, etc ), in order to cause the allergic red blood cell to have a cohesive reaction. Clinically, the so-called "same blood" refers to the fact that the ABO blood type system is the same as the Rh Blood type system, and other red blood type systems may not be the same. If the cross-configuration blood is not careful, or the blood is only used in saline, irregular antibodies outside the ABO blood type system may not be checked, and the antibody has an immune reaction with the corresponding antigen, it can lead to the occurrence of hemolytic transfusion reaction.

Although the positive rate of irregular antibody screening is low, once the patients enter red blood cells with the corresponding antigen, the antigen and antibody have immune binding, and the complement is involved, the input red blood cells are dissolved, that is, a hemolytic transfusion reaction occurs. The patient may experience fever, anemia, jaundice and hemoglobin, which may even endanger his life in severe cases. Therefore, we should always be cautious about the possibility of this transfusion reaction during blood transfusion. When the screening of irregular antibodies is positive, further antibody identification must be performed to determine its specificity, and then input red blood cells without the corresponding antigen to achieve safe blood transfusion.

Neonatal hemolytic disease (HDN) is also a passive immune disease caused by irregular IgG antibodies that do not work with fetal red blood cells in the mother. Any irregular antibody with IgG can theoretically cause HDN, because IgG antibodies can enter the fetal blood circulation through the placenta, damage fetal red blood cells, and lead to fetal edema, jaundice, anemia and liver and spleen enlargement, even concurrent nuclear jaundice. Therefore, irregular antibody screening should be performed for pregnant women with a history of blood transfusion or pregnancy. If irregular antibodies are detected, corresponding prevention and treatment should be performed. The antigen D in Rh blood type is stronger than that of eantigen, so the chance of producing anti-D antibody is higher than that of Anti-eantibody. Anti-A1 antibody is an irregular antibody in subtype A. Its presence reminds us to pay attention to irregular antibodies other than the ABO blood type, while also attaching great importance to irregular antibodies in the Abo subtype, because it is also a factor that causes the hemolytic transfusion reaction. The anti-M Antibody is a cool-down pigment and rarely active at 37 ℃. Generally, it does not cause hemolysis in the body. However, it should be noted during the operation when the patient is under low-temperature anesthesia because such antibodies can activate complement. When the body temperature is within the optimal response temperature range of cold antibodies (4 ~ 20 deg C), there may be a hemolysis reaction.

Most irregular antibodies are produced in the Rh Blood type system. In addition to anti-D, other antibodies, such as anti-E, anti-EC, and anti-ce, also have a high detection rate, it is suggested that blood transfusion in RH-positive patients may also cause hemolysis, and the probability is high. according to the distribution of Rh antigen in Chinese Han population, eantigen-positive ratio is lower than D Antigen-positive, and the probability of producing eantibody is higher than that of Anti-D antibody, therefore, transfusion of Rh Blood Type System D Antigen-positive eantigen-negative cannot be ignored. the rate of anti-D produced by Rh-negative individuals is 70.9%. the potency of the produced antibodies gradually decreases in the body, and even regular tests may be missed. If Rh (d) is input as the recipient of the blood) when positive blood stimulation occurs, there will soon be an immune recall reaction. the antibody potency ranges from 1 ~ The peak reached within 2 weeks, causing delayed vascular hemolysis, and occurred several days after blood transfusion. the blood transfusion is ineffective and hemolysis is easily ignored by the clinic. the intensity of the hemolysis reaction is proportional to the antibody potency. The antibody production intensity increases, and the more serious the hemolysis reaction is. anti-M, anti-Lea, and anti-P1 are rare, but anti-Lea antibody can cause severe hemolytic transfusion reaction, so it cannot be used as a blood donor. If it is a person of the blood, you should give le (a-B -) blood input. it has clinical significance only when the antibody is positive for 37 ℃ or immunoglobulin test. the optimal reaction temperature for anti-P1 is 4 ℃, which can be found at 37 ℃. anti-P1 antibodies rarely cause hemolysis in the body, and almost always do IgM-type antibodies. Therefore, they do not pass through the placenta and do not cause HDN. cool-gins can be ignored during blood configuration. we still follow the general principles of blood transfusion because of the fact that there are many antibodies in hemolytic anemia.

In conclusion, irregular antibodies are one of the main factors that cause hemolytic transfusion reaction and neonatal hemolytic disease. They are of clinical significance for the diagnosis of renal failure and death cases caused by blood transfusion. Therefore, in order to ensure the safety of blood transfusion, improve the efficacy of blood transfusion, and reduce or eliminate the occurrence of hemolytic transfusion reactions, irregular antibody testing must be one of the important items of pre-transfusion examination.