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 not the same as it was before. Is this possible, and if so, in what cases?
What is a blood type and what does it depend on
According to the generally accepted classification, it is customary to distinguish 4 blood groups and two Rh factors – positive and negative, which are determined depending on its composition.
On the surface of red blood cells (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 red blood cells, such blood is designated “0”, and this is the first group. In the presence of an A–antigen, the group receives the appropriate 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 widespread 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 – Rh positive, absent – negative. The vast majority of people (about 85%) are carriers of the group with a positive Rh factor.
Because of what the blood type may change
The presence or absence of certain protein substances in the body that affect the determination of its group depends on the genotype, that is, DNA. And this characteristic is innate and unable to change during life. Therefore, spontaneous or spontaneous changes in blood type are considered impossible.
The only case when theoretically the composition of antibodies in plasma can change is bone marrow transplantation. And only on condition that the recipient’s “native” bone marrow 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 has been transplanted bone marrow, which 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” is always selected for transplantation. That is, the blood type of the donor should be the same. Otherwise, the body will perceive the transplanted tissues as foreign and start the process of rejection.
What else can cause changes
It is possible to determine the blood type only by laboratory analysis. To do this, the sample is mixed with serums containing different types of antibodies and it is observed in which cases the bonding of red blood cells occurs. But sometimes in the course of such an analysis, you can get the wrong result. One of the reasons, though 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 earlier. In such cases, they do not talk about changing the group, but about distorting the results of the analysis. And this can happen for a number of objective reasons.
Against the background of some infectious diseases, the body produces specific enzymes that, when they get into the blood, cause the cleavage of part of antigen A, which is why it acquires the signs of antigen B. This process does not affect the plasma composition in any way, but if an analysis is done at this time, it is likely to get a distorted result. If you repeat the study after recovery, the reaction will indicate the correct group.
Diseases affecting blood composition
Some diseases are accompanied by increased production of red blood cells. Against the background of an excessively large number of red blood cells, the antibodies reach a concentration insufficient for the chemical reaction that determines the group. As a result, the studies also show the wrong result.
The change also occurs in patients with myeloid leukemia, an oncological disease during which the number of degenerated white blood cells in the plasma rapidly increases, and the concentration of antigens decreases.
The influence of bacteria
Bacteria can also affect the blood type. Studying the gut microbiota, scientists have discovered a bacterium that is able to change groups A and B to 0, cutting off the corresponding antigens. But such changes are also temporary – they persist as long as there is a bacterium in the body, then the group becomes the same as before.
It is during pregnancy that many women discover a “change in blood type”. The reason is also in the number of red blood cells. Red cells are produced by the bone marrow more intensively during pregnancy than during 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 shell 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 actually exists. In addition, the results of a laboratory study may be distorted in the presence of proteins in the body, which in certain circumstances demonstrate the same characteristics as the substances responsible for the “plus” rhesus.
In addition, in the history of modern medicine, there is one known case of a change in the Rh factor, which has not yet found a scientific explanation. Nine-year-old girl Demi Lee Brennan had a liver transplant, after which her blood turned from the first “negative” into the first “positive”. But there are no more such cases known to world medicine.
Does the blood type change after transfusion
There are certain rules for blood transfusion. Thus, people with the fourth (AB) group are considered universal recipients. Since their red blood cells contain both types of antigens, then blood of any group will suit 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, will suit everyone, but a person with 0 blood can only take the same. In practice, during transfusion, they try to select the donor material that best matches the characteristics of the recipient’s plasma.
If a person is injected with blood 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 “foreign” blood was injected, a fatal outcome occurs.
When injecting compatible donor material, health problems usually do not occur (if the Rh factor is also suitable) and such a procedure will not cause changes in the recipient’s blood group either.
If we summarize the above, then the blood type is a stable innate characteristic. And when the analyses show changes, it is usually a temporary phenomenon caused by certain factors.