Rules for determining the blood type according to the ABO system

The procedure for determining blood groups according to the ABO systemis to identify antigens A and B in erythrocytes using standard antibodies and the use of agglutinins in the plasma or serum of the blood being analyzed by standard red blood cells. The technique was developed at the beginning of the 20th century and is still actively used in medicine. Determination of antigens A and B is due to anti-A and anti-B zeolitons.

Basic concepts

Donors are always determined not only by antigensin erythrocytes, but also agglutinins in serum (plasma) using standard erythrocytes. Venous blood is used as a biomaterial. Before the test, you must give up fatty foods a day before the test and do not smoke for half an hour before taking the test. Blood groups are determined twice: first in the treatment department, where the material is harvested, and then confirmed by a study in the laboratory.

The definition of blood groups according to the ABO system isthe main test used in transfusiology. Also, a similar system of blood groups is present in some animals, for example in chimpanzees, gorillas and bonobos.

History of discovery

In science, there is a generally accepted view thatthe method of determining blood groups according to the ABO system was first revealed by Karl Landsteiner, an Austrian scientist, in 1900. Then he described in his work three types of antigens. For this in thirty years he was awarded the Nobel Prize in Medicine and Physiology. Due to the fact that there was no close relationship between the scientists, they later established that the Czech serologist Jan Janski, regardless of the researches of K. Landsteiner, described for the first time four human blood groups, but his studies were not known to a wide audience. At present, it is the classification developed by J. Jansky that is applied in Russia and the republics of the former USSR. In the USA, WL Moss created his similar work in 1910.

The method of determining blood groups according to the ABO system using tsoliklonov

The blood group should be determined indoors withgood lighting with a temperature range of 15 to 25 degrees Celsius, since deviations from this norm may affect the results of the study. The initials and surname of the patient are written on the plate or plate. From left to right or around the circle, the standard notation for groups (O (I), A (II), B (III)) is applied. Below them, appropriate serums are placed dropwise by separate pipettes for each species. Then the patient's blood is added to them. The material for research is taken from the earlobe or finger. This requires the technique of determining the blood group according to the ABO system.

The use of erythrocytes,which are in the tube after the clot forms. It is necessary that the amount of serum was more than the amount of added blood tenfold. After that, the drops are mixed with glass sticks (separately for each). Within five minutes, gently rocking the plate, watching for the appearance of a hemagglutination reaction. It is found in the fact that small red lumps appear, merging into larger ones. Serum at this time almost completely loses color.

In order to eliminate false hemagglutinationsimple gluing of erythrocytes, it is necessary to add one drop of physiological solution after three minutes and check whether agglutination remains. If so, then it is true. Everything, the definition of blood groups according to the ABO system on this is completed.

Interpretation of results

As a result, there can be four reactions:

• there is no agglutination with any of the sera - the first group of O (I);
• the reaction was manifested with the sera I (ab) and III (a) - the second group A (II);
• agglutination occurs with the sera I (ab) and II (b) - the third group B (III);
• if the reaction occurs with three sera,It is necessary to carry out an additional procedure with AB (IV) group reagents, which are standard; if there is no agglutination in such a drop, we can assume that this is the 4th blood group AB (IV).

Express method for Rh factor

The method of determining blood groups according to the ABO system assumes simultaneous detection of the Rh factor (Rh).

The surface of the plate is pre-wetted andthey write on it "control serum" and "antiresus serum". Then one or two drops of the necessary reagents are placed under the inscriptions and the analyzed material is added to them. To do this, you can also use blood from the finger (in the same amount as the volume of the serum) or red blood cells left on the bottom of the tube after the appearance of the clot (half the volume of serum). The choice of material for the final result is not affected. Then, the blood and serum are mixed with a dry glass rod, after which they wait for the reaction to occur for five minutes. In order to eliminate false readings, after three to four minutes, an isotonic solution of sodium chloride (just a few drops) is added. The determination of the blood group according to the ABO and Rh system is very often carried out.

If the agglutination of erythrocytes in a drop withserum occurs, this indicates a positive Rhesus blood. According to statistics, Rh + occurs in 85% of the world's population. The lack of it allows us to talk about Rh-negative affiliation. If agglutination appeared in the control serum, then it has become unusable. Unfortunately, the algorithm for determining the blood group according to the ABO system does not always work perfectly.

What mistakes can be made with this technique?

Inaccuracies in determining the blood belonging to a particular group depend on the following reasons:

• Technical.
• Biological specificity of the blood.
• The incomplete nature of the standard sera and erythrocytes.

Technical Errors

Possible errors in determining the blood group of the ABO system in a cross way:

• Incorrect serum on the plate.
• Wrong quantitative proportions of the material.
• Use of insufficiently clean plates orplates that come in contact with blood (each serum should be collected by a separate pipette, which should be washed with a solution of sodium chloride (at a concentration of 0.9%)).
• Incorrect record of the analyzed material.
• Non-observance of the time required forthe onset of agglutination - it is not necessary to hurry and take into account the reaction before the expiry of five minutes, because the blood may have weak agglutinogens. To overdo it is also not necessary, because the drops can dry from the edges and lead to a false conclusion. It is important to follow the rules for determining the blood group according to the ABO system.
  
• Erroneous centrifugation can also lead to a false result.
• Air temperature exceeding permissible,affects the absence of agglutination. To avoid mistakes of this kind, you need to use a special serum, designed to work in hot climates. Determine blood groups on a plate or plate, the outer surface of which falls into cold water.

Biological specificity errors

Errors associated with the biological specificity of the blood being analyzed are divided into two types.

• Dependent on the characteristics of red blood cells.
• Errors due to the biological characteristics of the serum.

Let's consider each species in more detail.

Dependent on the characteristics of red blood cells

• Late agglutination, due to "weak"forms of erythrocytes and antigens. In order to avoid mistakes, it is necessary to determine the blood group of donors and recipients using standard erythrocytes. Identify agglutinogen A₂ should be re-examined with other types of reagents and other dishes, increasing the reaction recording time.
• "Panagglutination" ("autoagglutination") - skillblood to show the same reaction of a non-specific nature with all sera, including its own. After five minutes, the acuteness of such agglutination weakens, although it should intensify. Similar cases are observed in cancer patients, burned, etc. As control it is necessary to evaluate the manifestation of agglutination of the analyzed erythrocytes in standard serum of the fourth group and saline solution. At "panagglutination" the blood group is determined as a result of triple washing of erythrocytes. If it does not give the desired result, it is worth re-sampling the blood sample in a preheated tube and place the sample in a thermo container to help maintain a temperature of 37 degrees Celsius and above. Then it should be delivered to a laboratory where the above temperature is maintained and heated physiological saline, plate and reagents are used.

• Sometimes the red blood cells of the blood being analyzedare arranged as "coins", and they can be taken as agglutinates. If you add two drops of isotonic solution and gently shake the plate, the red blood cells take the correct position.
• Incomplete or mixed agglutination occurring in patients with second, third and fourth groups as a result of bone marrow transplantation or in the first three months after blood transfusion 0 (I).

Due to the biological characteristics of the serum

• During routine testing as a resultthe previous sensitization revealed antibodies of a different specificity. We need to determine it and pick up red blood cells without the content of the antigen to which immunization is detected. The recipient must necessarily select compatible donor blood individually.
• There are no antibodies A and B, which is observed in newborns and patients suffering from oppression of humoral immunity.
• When forming "coins" anomalousthe result must be confirmed by taking the standard red blood cells of the first group. A solution of sodium chloride and rocking the plate help differentiate the real agglutinates and "coins".
  

Errors associated with the use of inferior standard erythrocytes and sera

Weak sera with past shelf life or having a titer of less than 1:32 are able to initiate weak and late agglutination. The use of such reagents is unacceptable.

Use of unsuitable standard red blood cellsor whey, prepared under non-sterile conditions and conserved to an insufficient degree, leads to the appearance of "bacterial" agglutination, which is of a nonspecific nature.

There are many popular assumptions aboutblood groups of the ABO system, which appeared immediately after its detection in various world cultures. So, for example, in the 30s of the last century in Japan and some other countries, the theory that linked the blood group to one or another type of personality gained popularity. Similar theories are popular today.

There is also the opinion that a person who has group A is subject to a severe hangover, O is associated with good teeth, and group A2 - with the highest level of IQ. But such assertions are not scientifically proven.

We examined the definition of blood groups using the ABO system using standard sera.