Antipyretics for children are prescribed by a pediatrician. But there are emergency situations with fever when the child needs to be given medicine immediately. Then the parents take responsibility and use antipyretic drugs. What is allowed to be given to infants? How can you lower the temperature in older children? What medications are the safest?
Passive agglutination reactions. Indirect agglutination reactions. Indirect or passive hemagglutination reaction (IRHA, RPHA). Reverse RNGA. Passive hemagglutination inhibition reaction (PHA).
These reactions are called indirect (passive), since they use Ag (or AT) artificially sorbed on the surface of various corpuscular particles.
Indirect or passive hemagglutination reaction (RNGA, RPGA) is one of the most sensitive serological reactions. It is based on the ability of AT to interact with Ag fixed on various red blood cells, which then agglutinate. For greater stability of diagnosticums, red blood cells are formalinized.
Reverse RNGA used to detect Ag in blood serum; For this purpose, not Ag, but AT are fixed on erythrocytes. Reactions of this type are widely used to diagnose infectious diseases, establish pregnancy, detect hypersensitivity to drugs, etc.
Passive hemagglutination inhibition reaction (RTPGA) - further development RNGA; in a sense controls its specificity. Unlike RNGA, includes three components; Ag, AT and Ag (AT) adsorbed on erythrocytes. Initially, Ag reacts with AT (standard antiserum), then erythrocytes sensitized with the same Ag (or AT) are added to the mixture. If, during the interaction of Ag with AT, no free AT (or Ag) remains in the system, then agglutination of the erythrocyte diagnosticum is not observed.
Table of contents of the topic "Immunomodulators. Immunodiagnosis of infectious diseases.":Detailed agglutination reaction (RA). To determine AT in the patient’s blood serum, a extensive agglutination reaction (RA). To do this, a diagnosticum is added to a series of dilutions of blood serum - a suspension of killed microorganisms or particles with sorbed Ag. The maximum dilution giving agglutination Ag is called the serum titer.
Types of agglutination reaction (RA) to detect AT - a blood-drop test for tularemia (with a diagnosticum applied to a drop of blood and the appearance of visible whitish agglutinates) and the Huddleson test for brucellosis (with a diagnosticum stained with gentian violet applied to a drop of blood serum).
Approximate agglutination reaction (RA)
To identify the isolated microorganisms, an approximate RA is placed on glass slides. To do this, a pathogen culture is added to a drop of standard diagnostic antiserum (diluted 1:10, 1:20). At positive result perform a detailed reaction with increasing dilutions of the antiserum.
Reaction considered positive if agglutination is observed in dilutions close to the titer of the diagnostic serum.
OAS. Somatic O-Ags are heat stable and can withstand boiling for 2 hours. When interacting with AT, they form fine-grained aggregates.
N-Ag. N-Ag (flagellates) are thermolabile and quickly degrade at 100 °C, as well as under the influence of ethanol. In reactions with H-antiserum, after 2 hours of incubation, loose large flakes are formed (formed by bacteria sticking together with flagella).
Vi-Ar typhoid bacteria is relatively heat-stable (withstands temperatures of 60-62 °C for 2 hours); When incubated with Vi antiserum, a fine-grained agglutinate is formed.
Direct hemagglutination reactions
The simplest of these reactions - agglutination red blood cells, or hemagglutination, used to determine blood groups in the ABO system. For determining agglutination(or lack thereof) use standard antisera with anti-A and anti-B agglutinins. The reaction is called direct, since the Ags being studied are natural components of red blood cells.
Common with direct hemagglutination viral hemagglutination has mechanisms. Many viruses are capable of spontaneously agglutinating erythrocytes of birds and mammals; their addition to a suspension of erythrocytes causes the formation of aggregates from them.
Agglutination reactions are based on the interaction of a reagent (antibodies) with antigens located on the surface of cells or foreign particles. As a result, large aggregates are formed, which precipitate and can be seen even with the naked eye. In this way, the blood group is determined according to the ABO system, the presence of the Rh factor in it, etc. This is a more sensitive diagnostic method compared to precipitation reactions, since the volume of sediment (agglutinate) exceeds the volume of precipitate.
Direct hemagglutination
The direct hemagglutination reaction (DHR) is used to detect surface antigens of microorganisms and red blood cells, as well as antibodies to them.The test material (blood) is added to standard sera containing antibodies. The speed of the direct agglutination reaction is related to the amount of material being tested, the amount and concentration of serum, and ambient temperature.
Indirect hemagglutination
The indirect hemagglutination reaction is carried out to detect antibodies in the patient’s blood using an erythrocyte diagnosticum. The reagent consists of red blood cells on the surface of which there is an antigen (proteins of microorganisms, toxins, allergens, etc.).The patient's blood serum is diluted with 0.9% sodium chloride solution, then erythrocyte diagnosticum is added and the result is monitored. This highly sensitive diagnostic method detects antigens even in small concentrations.
Hemagglutination inhibition reaction
Hemagglutination reaction
Agglutination reaction
Agglutination reaction (RA) is the gluing and precipitation of microbes or other cells under the influence of antibodies in the presence of an electrolyte (isotonic sodium chloride solution). The resulting precipitate is called agglutinate.
For the reaction you need:
1. Antibodies (agglutinins) - are found in the patient’s serum or in immune serum.
2. Antigen - a suspension of living or killed microorganisms, red blood cells or other cells.
3. Isotonic solution.
The agglutination reaction for serodiagnosis is widely used for typhoid fever, paratyphoid fever (Vidal reaction), brucellosis (Wright reaction), etc. The antibody is the patient's serum, and the antigen is a known microbe.
When identifying microbes or other cells, their suspension is used as an antigen, and a known immune serum is used as an antibody. This reaction is widely used in diagnostics intestinal infections, whooping cough, etc.
In laboratory practice, two hemagglutination reactions (HRAs) differing in their mechanism of action are used.
First RGA refers to serological. In this reaction, red blood cells are agglutinated when interacting with appropriate antibodies (hemagglutinins). The reaction is widely used to determine blood groups.
Second RGA is not serological. In it, the gluing of red blood cells is caused not by antibodies, but by special substances formed by viruses. For example, the influenza virus agglutinates the red blood cells of chickens and guinea pigs, and the polio virus agglutinates the red blood cells of sheep. This reaction makes it possible to judge the presence of a particular virus in the material under study.
This is a serological reaction in which specific antiviral antibodies, interacting with the virus (antigen), neutralize it and deprive it of the ability to agglutinate red blood cells, i.e., inhibit the hemagglutination reaction. The high specificity of the hemagglutination inhibition reaction (HAI) allows it to be used to determine the type and even the type of viruses detected during the HRA test.
The indirect (passive) hemagglutination reaction (IRHA) is based on the fact that red blood cells, if a soluble antigen is adsorbed on their surface, acquire the ability to agglutinate when interacting with antibodies to the adsorbed antigen. The RNGA diagram is shown in Fig. RNGA is widely used in the diagnosis of a number of infections.
Rice. Scheme of the passive hemagglutination reaction (RPHA). A - obtaining an erythrocyte diagnosticum; B - RNGA: 1-erythrocyte: 2 - antigen being studied; 3 - erythrocyte diagnosticum; 4 - antibody to the antigen being studied: 5 - agglutinate.
Using RNGA, you can determine an unknown antigen if known antibodies are adsorbed onto erythrocytes.
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Serological reactions are designated in accordance with the phenomena accompanying the formation of the antigen-antibody complex during the interaction of components with different properties. There are reactions of agglutination, precipitation and lysis.
Agglutination reaction (RA)
The agglutination reaction (RA) is based on the use of a corpuscular antigen (a suspension of bacteria, sensitized erythrocytes, latex particles, etc.) interacting with specific antibodies, as a result of which the resulting antigen-antibody complex precipitates. This reaction is widely used in laboratory practice for serological diagnostics bacterial infections and for identification of isolated microorganisms.
RA is used to diagnose many infectious diseases: brucellosis (Wright, Heddleson reaction), tularemia, leptospirosis (RAL - Leptospira agglutination and lysis reaction), listeriosis, typhus (RAR - Rickettsia agglutination reaction), shigellosis, yersiniosis, pseudotuberculosis, etc.
Indirect or passive agglutination reaction (RIGA or RPGA).
To stage this reaction, red blood cells of animals (sheep, monkey, guinea pigs, some birds) sensitized with antibodies or antigen are used, which is achieved by incubating a suspension of red blood cells and a solution of antigen or immune serum.
Diagnosticums obtained on the basis of erythrocytes sensitized with antigens are called antigen erythrocyte diagnosticums. They are intended for the determination of antibodies in serial dilutions of blood sera, for example, erythrocyte shigella diagnosticums, erythrocyte salmonella O-diagnosticums.
Accordingly, diagnostics based on erythrocytes sensitized with specific immunoglobulins are called antibodies(immunoglobulin) diagnosticums and they serve to detect antigens in various materials, for example, erythrocyte immunoglobulin diphtheria diagnosticum for RIGA, used to detect diphtheria exotoxin of corynebacteria in a liquid nutrient medium when material from the nose and oropharynx is inoculated into it.
The hemagglutination reaction is used to diagnose both bacterial (typhoid fever, paratyphoid fever, dysentery, brucellosis, plague, cholera, etc.) and viral (influenza, adenoviral infections, measles, etc.) infections. In terms of sensitivity and specificity, RIGA is superior to RA.
Hemagglutination inhibition reaction (HAI)
The hemagglutination inhibition reaction (HAI) is used to titrate antiviral antibodies in blood serum, as well as to establish the type of isolated viral cultures. RTGA can be used to diagnose those viral infections, the pathogens of which have hemagglutinating properties.
The principle of the method is that serum containing antibodies to a specific type of virus suppresses its hemagglutinating activity and the red blood cells remain non-agglutinated.
Passive hemagglutination inhibition (delay) reaction (RPHA).
Three components are involved in RTPGA: immune serum, antigen (test material) and sensitized erythrocytes.
If the test material contains an antigen that specifically reacts with the antibodies of the immune standard serum, then it binds them, and with the subsequent addition of erythrocytes sensitized with an antigen homologous to the serum, hemagglutination does not occur.
RTPHA is used to detect microbial antigens, for their quantitative determination, and also to control the specificity of RTPGA.
Latex agglutination reaction (RLA)
Latex particles are used as a carrier of antibodies (immunoglobulins). RLA is an express method for diagnosing infectious diseases, taking into account the time required (up to 10 minutes) and the ability to detect antigen in a small volume of test material.
RLA is used to indicate antigens of Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis in cerebrospinal fluid, to detect group A streptococci in throat swabs, to diagnose salmonellosis, yersiniosis and other diseases. The sensitivity of the method is 1-10 ng/ml, or 10³ -10⁶ bacterial cells in 1 µl.
Coagglutination reaction (CoA)
The coagglutination reaction (CoA) is based on the ability of protein A of staphylococci to attach specific immunoglobulins. RCA - a method of express diagnostics - serves to identify soluble thermostable antigens in human secretions and in the composition of circulating immune complexes (CIC). Detection of specific antigens in the composition of the CEC requires their preliminary precipitation from blood serum.
Precipitation reaction
In the precipitation reaction (RP), as a result of the interaction of antibodies with highly dispersed soluble antigens (proteins, polysaccharides), complexes are formed with the participation of complement - precipitates. It is a sensitive test used to detect and characterize a variety of antigens and antibodies. The simplest example of high-quality RP is the formation of an opaque precipitation band in a test tube at the boundary of the antigen layering on the immune serum - the ring precipitation reaction. Various types of RP in semi-liquid agar or agarose gels are widely used (double immunodiffusion method, radial immunodiffusion method, immunoelectrophoresis).
Complement fixation reaction (CFR)
The complement fixation reaction (CFR) is based on the phenomenon of hemolysis with the participation of complement, i.e. capable of detecting only complement-fixing antibodies.
RSC is widely used for the diagnosis of many bacterial and viral infections, rickettsial infections, chlamydia, infectious mononucleosis, protozoal infections, helminthiasis. RSC is a complex serological reaction in which two systems are involved: the test (blood serum), represented by the antigen-antibody and complement system, and the hemolytic (sheep red blood cells + hemolytic serum). Hemolytic serum is heat-inactivated rabbit blood serum immunized with sheep erythrocytes. It contains antibodies against sheep red blood cells.
A positive RSC result - the absence of hemolysis - is observed if the test serum contains antibodies homologous to the antigen. In this case, the resulting antigen-antibody complex binds complement, and in the absence of free complement, the addition of the hemolytic system is not accompanied by hemolysis. If there are no antibodies corresponding to the antigen in the serum, the formation of an antigen-antibody complex does not occur, complement remains free and the serum causes hemolysis of red blood cells, i.e. the presence of hemolysis is negative result reactions.
Yushchuk N.D., Vengerov Yu.Ya.
