Blood agglutination is the agglutination and sedimentation of red blood cells, bacteria and other cells that carry antigens.
The process occurs under the influence of agglutinins, which are specific substances. Lectins or antibodies act as these substances.
Possible types of agglutination when determining blood group
Agglutination is specific and non-specific. In the first case, the reaction occurs with the participation of three components:
- antigens;
- antibodies;
- electrolytes (use isotonic solution).
All possible types of agglutination are used when determining the blood group, but this is not the only case.
For what purpose is it used?
The blood agglutination test is used to identify the causative agent of an infectious disease. At the same time, it settles, and it is easy to detect it in the sediment. This process is used, as mentioned above, in determining the blood type. This is what we will discuss next.
What are the features?
Erythrocytes contain type A and B antigens. Theybind to antibodies ά and β, respectively. Blood groups and agglutination reactions:
- 1, 0 (ά, β) - no antigens on the surface of erythrocytes;
- 2, A (β) – antigen A and antibody β present;
- 3, B (ά) - contains antigen B and antibody ά;
- 4, AB (00) – two antigens present, 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's body. In other words, she has antibodies to the blood antigens of the unborn child. In this case, an incompatibility occurs. In addition, the blood type must be taken into account when transfusing.
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 is necessary to 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 different laboratories may not have the same ranges of obtained values, 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 rods;
- standard isohemagglutinating sera;
- dry earthenware plates that are divided into 4 sectors.
There are requirements for the conditions of the test:
- daylight;
- room temperature above +16 ˚С;
- using blood and serum volumes in a ratio of 1:10;
- Reliable results within 5 minutes.
The above are the main conditions and tools. Blood agglutination can be carried out in several ways, and each of them puts forward individual requirements.
Methods
Possible methods for determining blood group using agglutination:
- standard method;
- cross-reaction;
- use of tsoliclones;
- express method using the "Erythrotest-Groupcard" set.
Standard method
Blood agglutination is manifested using the patient's red blood cells. Standard sera are also used, which contain known antigens.
One drop of four serums is placed on a flat plate. Then, using glass rods, the patient's blood to be examined is introduced onto it. In this case, it is convenient to use eyedroppers. The ratio should be 1:10. Serum and blood are gently mixed. Evaluation can be done within five minutes.
Deciphering test results with a simple method
After the specified timein drops of serum enlightenment is observed. In some, you can see that erythrocyte agglutination has occurred (small flakes), in others it is absent.
The following options exist:
- no reaction in all serum samples − 1 group;
- clotting occurred everywhere except for the 2nd sample - group 2;
- no reaction only in the 3rd sample - 3rd group;
- agglutination occurred everywhere – group 4.
Thus, the main thing is to properly distribute the serum. Then it will not be difficult to decipher the result. If blood agglutination is weak, it is recommended to re-test. In the case of small flakes, they are examined under a microscope.
Cross Reaction
Sometimes it is impossible to accurately determine the blood type in a simple way. Agglutination in this case is carried out using the cross-reaction method. Unlike the first version of the test, standard erythrocytes are important here. The patient's blood is collected in a test tube, centrifuged, and then the serum is pumped out with a pipette for further research.
It is placed on a plate in the amount of 2 drops, then standard erythrocytes of groups A and B are added to it. The contents are stirred by shaking the container.
Results of the cross-reaction method
After five minutes, samples are ready for review. The options are:
- gluing occurred in both drops – 1 group;
- flakes are notobserved in none of the samples – group 4;
- the process is visible in one sample - 2nd or 3rd group (depending on where exactly the blood clotted).
Coliclon method
To determine the blood type, agglutination in this way is carried out using synthetic serum substitutes. They are called tsoliklones. They contain artificial substitutes for ά and β-agglutins known as erythrotests (pink and blue, respectively). The reaction takes place between them and the patient's red blood cells.
This method is the most accurate and reliable. Basically, it does not require re-examination. The 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 type must necessarily be confirmed by a reaction with a specific synthetic substitute (anti-AB). In addition, it does not show sticking when sodium chloride solution is added.
Express-method with a set of "Erythrotest-group cards"
Considering the possible methods of analysis in determining the blood type, it is worth noting that this method has its own characteristics. They lie 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 well card with dried reagents already present at the bottom. 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 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 that, blood is added, slightly stirred. In three minutes, the result will be received.
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, the erythrocytes simply fold in the form of coin columns. If you add a couple of drops of saline, they disintegrate. A similar phenomenon is recognized under a microscope.
- Cold agglutination of blood. Such a reaction is observed if the conditions for the study were unfavorable. When the temperature is below +16˚C, bonding may occur.
- Panaagglutination. If there is an infection in the blood, test results may be false. This phenomenon is also possible in the case of oncological diseases, 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 follow the recommendations of the doctor when preparing for this procedure. With regard to medical personnel, their task is to create favorable conditions andcompliance with all rules. This is the only way to achieve accurate results when performing blood agglutination.
