Agglutination of blood is gluing and sedimentation in the form of a precipitate of red blood cells, bacteria and other cells that carry antigens.
The process occurs under the influence of agglutinins, which are specific substances. The role of these substances are lectins or antibodies.
Possible types of agglutination in determining the blood group
Agglutination is specific and non-specific. In the first case, the reaction occurs with the participation of three components:
- antigens;
- antibodies;
- electrolytes (isotonic solution is used).
All possible types of agglutination are used in determining the blood group, but this is not the only case.
What is it used for?
The blood agglutination reaction is used to identify the causative agent of an infectious disease. However, it settles, and it is easy to detect in the sediment. This process is used, as mentioned above, and in determining the blood type. This is what will be discussed further.
What are the features?
Red blood cells contain type A and B antigens. They bind to antibodies ά and β, respectively. Blood groups and agglutination reactions:
- 1, 0 (ά, β) - there are no antigens on the surface of red blood cells;
- 2, A (β) - antigen A and antibody β are present;
- 3, B (ά) - contains antigen B and antibody ά;
- 4, AB (00) - there are two antigens, no antibodies.
It is worth noting that antigens are already observed in the embryo. As for antibodies, they appear after birth, in the first month of life.
The compatibility of people depends on the blood type. This is the reason for the rejection of the fetus by the mother. In other words, she has antibodies to her baby’s blood antigens. In this case, incompatibility occurs. In addition, the blood group must be taken into account during transfusion.
Preparation
Blood groups and agglutination reactions are compatible concepts that are often used in medicine.
Before the test, it is important to follow certain instructions. It should temporarily exclude the use of certain foods and drugs. This will help make the results more accurate. Recommendations to be followed are prescribed by the doctor. The fact is that in different laboratories the ranges of the obtained values may not coincide, that is, they are slightly different.
Test conditions
In order for the blood type to be determined accurately, it is important to choose the right equipment. These include:
- saline and pipette;
- glass sticks;
- standard isohemagglutinating serums;
- dry earthenware plates, which are divided into 4 sectors.
There are requirements for the test conditions:
- daylight;
- the temperature in the room is above +16 ˚;
- the use of blood and serum in a ratio of 1:10;
- reliable results are obtained within 5 minutes.
The basic conditions and tools are presented above. Blood agglutination can be carried out in several ways, and each of them puts forward individual requirements.
Methods
Possible methods for determining the blood group using agglutination:
- standard method;
- cross reaction;
- use of cyclones;
- express method using the Erytrotest group cards set.
Standard method
Blood agglutination is manifested using red blood cells of the patient. Standard serums that contain known antigens are also used.
On a flat plate is placed 1 drop of four sera. Then, with the help of glass rods, blood of the patient to be examined is introduced onto it. In this case, it is convenient to use eye pipettes. A ratio of 1:10 should be followed. Serum and blood mix gently. An assessment can be made within five minutes.
Deciphering test results using a simple method
After the specified time in drops of serum, enlightenment is observed. In some, it can be seen that erythrocyte agglutination has occurred (small flakes), in others it is absent.
The options are as follows:
- there is no reaction in all serum samples - group 1;
- coagulation occurred everywhere, except for 2 samples - 2 group;
- lack of reaction in only 3 samples - 3 group;
- agglutination occurred everywhere - group 4.
Thus, the main thing is to properly distribute the serum. Then deciphering the result is not difficult. If blood agglutination is weak, it is recommended that the analysis be repeated. In the case of small flakes, they are examined under a microscope.
Cross reaction
Sometimes in a simple way it is impossible to accurately determine the blood group. Agglutination in this case is carried out using the cross-reaction method. Unlike the first test variant, standard red blood cells are important here. The patient’s blood is collected in a test tube, centrifuged, and then serum is pumped out with a pipette for further research.
It in the amount of 2 drops is placed on a plate, then standard red blood cells of groups A and B are added to it. The contents are stirred by shaking the container.
Cross Reaction Method Results
Five minutes later, the samples are ready for review. Options are as follows:
- bonding occurred in both drops - 1 group;
- flakes are not observed in any of the samples - group 4;
- the process is visible in one sample - group 2 or 3 (depending on where exactly the blood coagulated).
The cyclonic method
To determine the blood group, agglutination in this way is carried out using synthetic serum substitutes. They are called cyclones. They contain artificial substitutes for ά and β-agglutins, known as erythrotests (pink and blue, respectively). The reaction occurs between them and the red blood cells of the patient.
This method is the most accurate and reliable. Basically, it does not require re-conducting the study. Evaluation of the results is carried out in the same way as in the case of the standard method. The peculiarity is that the fourth blood group must necessarily be confirmed by a reaction with a specific synthetic substitute (anti-AB). In addition, it does not adhere when adding sodium chloride solution.
Express methodology with a set of "Erythrotest group cards"
Considering the possible methods of analysis when determining the blood group, it is worth noting that this method has its own characteristics. They consist in the fact that the result can be evaluated not only in the laboratory, but also in the field. For the study, a special set is used. It includes a card with holes, at the bottom of which there are already dried reagents. In addition to anti-AB, anti-A and anti-B, anti-D is used to determine the Rh factor.
This method does not require special preparation, it is allowed to use blood that is taken from a finger, the presence of preservatives in it is allowed. First you need to add a drop of water to each well to dissolve the ingredients. After this, blood is added, mixes slightly. After three minutes, the result will be obtained.
False agglutination
Sometimes the data obtained after the test is not true. This phenomenon depends on certain factors.
There are three types of false reaction:
Pseudoagglutination True bonding does not occur, red blood cells simply add up in the form of coin columns. If you add a couple of drops of saline, they break up. A similar phenomenon is recognized under a microscope.
Cold blood agglutination. Such a reaction is observed if the conditions for the study were unfavorable. When the temperature is below +16 ° C, bonding may occur.
Panagglutination If there is an infection in the blood, the test results may be false. This phenomenon is also possible in the case of cancer, with sepsis.
Agglutination is very important in medicine. It allows not only to determine the blood group, but also to identify the causative agent of diseases, as well as the presence of infections. The main thing is to adhere to the doctor's recommendations in preparation for this procedure. As for the medical staff, its task is to create favorable conditions and compliance with all rules. Only in this way can accurate results be achieved when performing blood agglutination.