Causes and consequences of blood type changes

Many people know that blood type is an innate characteristic and it does not change throughout a person’s life. Nevertheless, on Internet forums you can often see the stories of people who, at some point, found out that their blood type is no longer the same as it was before. Is this possible, and if so, in what cases?

What is a blood group and what does it depend on?

According to the generally accepted classification, it is customary to distinguish between 4 blood groups and two Rh factors – positive and negative, which are determined depending on its composition.

On the surface of erythrocytes (red blood cells) there may be antigen molecules, for which it is customary to use the letters A and B. If there are no antigens on erythrocytes, such blood is designated “0”, and this is the first group. In the presence of the A-antigen, the group receives the corresponding name, it is also the second. The third is distinguished by the presence of antigen B molecules on erythrocytes, and the fourth contains both antigens at once, therefore it is designated as “AB”. In all other respects, there are no fundamental differences between the groups. The first is the oldest in terms of evolution and the most common in the world. The fourth is the youngest and its carriers are much smaller.

The Rh factor is also determined by the presence of an antigen. But already another – D. If it is present in the body – positive Rh, absent – negative. The vast majority of people (about 85%) are carriers of the Rh positive group.

What causes a blood type to change?

The presence or absence in the body of certain protein substances that affect the definition of its group depends on the genotype, that is, DNA. And this characteristic is innate and unable to change throughout life. Therefore, spontaneous or spontaneous changes in the blood group are considered impossible.

The only case where theoretically the composition of antibodies in plasma can change is bone marrow transplantation. And only on condition that the “native” bone marrow of the recipient died. The bone marrow is the main hematopoietic organ in the human body. It is he who produces red blood cells with certain antigens. Therefore, in theory, if a patient is transplanted with bone marrow that produces red blood cells that differ from those produced by the “native” organ, then the blood type will change. But all this is just a theory. In practice, an organ with the same characteristics as the “native” one is always chosen for transplantation. That is, the blood type of the donor must be the same. Otherwise, the body will perceive the transplanted tissues as foreign and start the process of rejection.

What else can cause change?

The blood group can only be determined by laboratory analysis. To do this, the sample is mixed with sera containing different types of antibodies and observed in which cases erythrocytes stick together. But sometimes in the course of such an analysis, you can get the wrong result. One of the reasons, although not the only one, is the error of the laboratory assistant. But there are cases when the analysis was carried out correctly, but still shows completely different data than was obtained before. In such cases, one speaks not of a change in the group, but of a distortion of the results of the analysis. And this can happen for a number of objective reasons.

Infection

Against the background of some infectious diseases, the body produces specific enzymes that, when they enter the blood, cause the splitting off of part of the A antigen, due to which it acquires the features of the B antigen. This process does not affect the composition of the plasma in any way, but if an analysis is made at this time, it is large chance of getting a misleading result. If you repeat the study after recovery, the reaction will indicate the correct group ^[1].

Diseases that affect the composition of the blood

Some diseases are accompanied by increased production of red blood cells. Against the background of an excessively large number of red blood cells, antibodies reach a concentration insufficient for the chemical reaction that determines the group. As a result, the study also shows an incorrect result.

The change also occurs in patients with myeloid leukemia, an oncological disease during which the number of degenerate white blood cells in the plasma rapidly increases, and the concentration of antigens decreases. ^[2].

Influence of bacteria

Bacteria can also affect blood type. Studying the intestinal microbiota, scientists have discovered a bacterium that can change groups A and B to 0, cutting off the corresponding antigens. ^[3]. But such changes are also temporary – they persist as long as the bacterium is present in the body, then the group becomes the same as before.

Pregnancy

It is during pregnancy that many women discover that they have a “blood type change”. The reason is also in the number of red blood cells. Red cells during childbearing are produced by the bone marrow more intensively than at other periods of life. As a result, the concentration of antibodies also changes, causing distortion of the test results.

Why does the Rh factor change?

Proteins responsible for determining the Rh factor “live” on the membrane of red blood cells. That is why, in the case of a strong increase in the number of red cells in the plasma, the analysis can show not only the wrong group, but also not the Rh factor that it actually is. In addition, the results of a laboratory study can be distorted if there are proteins in the body that, under certain circumstances, demonstrate the same characteristics as the substances responsible for the “plus” Rh.

In addition, in the history of modern medicine, one case of a change in the Rh factor is known, which has not yet found a scientific explanation. Nine-year-old girl Demi Lee Brennan underwent a liver transplant, after which her blood from the first “negative” turned into the first “positive”. But more such cases are not known to world medicine. ^[4].

Does blood type change after a transfusion?

There are certain rules for blood transfusion. So, people with the fourth (AB) group are considered universal recipients. Since their erythrocytes contain both types of antigens, blood of any group is suitable for them. But they can become a donor only for people with exactly the same blood. The first group, in which there are no antigens, on the contrary, is suitable for everyone, but a person with 0 blood can only take the same. In practice, when transfusing, they try to select donor material that best matches the characteristics of the recipient’s plasma.

If a person is injected with blood that is incompatible with his group, antibodies to foreign antigens are produced in the body, and red blood cells stick together, which leads to damage to internal organs. If more than 100 ml of “alien” blood was infused, a fatal outcome occurs.

With the infusion of compatible donor material, health problems usually do not arise (if the Rh factor is also suitable) and such a procedure will not cause changes in the recipient’s blood type either.

To summarize the above, the blood type is a stable congenital characteristic. And when analyzes show changes, it is usually a temporary phenomenon caused by certain factors.

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