Innate immune system includes physical and chemical barriers such as skin and mucus, floating proteins in plasma, such as complement proteins, alien ectopic cells such as neutrophils, macrophages, and natural lethal cells. Acquired or adaptive immunity has two important branches called cellular and humoral immunity. The most important cells are, T cell s in cellular immunity, and B cells in humoral immunity. The mechanisms of T cells are performed by themselves and partly by activated macrophages. B lymphocytes play a role in the production and secretion of immunoglobulins. Both of these cells are active against the antigen and give rise to specific responses.
Immunodeficiency means that immune system has inappropriate function, so that people are susceptible to a variety of infections. Immunodeficiency can be primary or secondary or be acquired. Most primary immunodeficiencies are due to genetic defects or immune function and have a genetic basis. In secondary immunodeficiencies, there are non-immune causes such as bacterial or viral infections, malnutrition or treatment. AIDS is the most famous secondary immunodeficiency disease.
Evaluation of immune system
Evaluation of immune system often begins with a CBC, peripheral blood platelet and ESR sedimentation test. The purpose of this study is to identify leukopenia, lymphopenia, neutropenia, neutrophilia and abnormal forms of peripheral blood cells and the probability of bacterial infection.
Function of B cells
Antibody deficiency is the most common type of immune defect, due to the lack of differentiation of B-lymphocytes in bone marrow or peripheral lymphatic encephalitis, and subsequently the inability of B-lymphocytes to secrete enough antibodies or to desirable quality. Patients with an initial deficiency of antibodies are susceptible to a variety of bacterial infections.
The first test to evaluate the function of Lymphocytes B is measuring serum immunoglobulins. Quantitative assays for IgA, IgG and IgM by ELISA or SRID methods are helpful in detecting the overall deficiency of immunoglobulins. It is also useful in identifying the deficiency of one or more immunoglobulin classes. In the study of B-lymphocytes, serum protein electrophoresis, immuno-electrophoresis and immunopharmation of electrophoresis have little or no quantitative sensitivity and capability.
Measuring serum immunoglobulins is the first test to evaluate the function of Lymphocytes B. Quantitative assays for IgA, IgG and IgM by ELISA or SRID methods are helpful in detecting the overall deficiency of immunoglobulins. It is also useful in identifying the deficiency of one or more immunoglobulin classes. In the study of B-lymphocytes, serum protein electrophoresis, immuno-electrophoresis and immunopharmation of electrophoresis have little or no quantitative sensitivity and capability.
- Patients with antibody deficiencies often have low serum antibodies, but sometimes amount of antibodies are normal, but their function is not normal.
- The most prevalent 88% deficiency is the IgA antibody deficiency.
- Common CVD is a syndrome characterized by decreasing antibodies in the bloodstream and the inability to produce antibodies with the normal number of peripheral B cells. Sexual distribution in CVID is roughly equal and affects men and women alike. The onset of recurrent infections in patients can begin at any age, but the first symptoms are more common in the age range of 1-5 and 16-20 years old.
Function of T cells
T lymphocytes have a more complex function than lymphocytes B. And so, their performance evaluation is more difficult. There are also simple, inexpensive, and reliable tests to check the function of T cells.
Delayed hypersensitivity reaction
This test is used with a set of antigens for screening in adults and children (with the exception of infants and infants). The positive result in delayed skin sensitivity testing in most cases is a sign of the normal functioning of T cells and cellular immunity. Of course, it should be noted that the positive result in the delayed skin sensitivity test performed with a group of antigens can not be a sign of the normal functioning of the immune system against other antigens. For example, in chronic mucosal-cardiovascular disease, immune function may be normal for all antigens other than Candida. In addition, the positive result of this test is the previous anti-human encounter. For example, people have received antigens through vaccine or infection, but in newborns they may still have not been exposed to some antigens. Thus, the test for skin allergy is negative, and this is a negative result of the disorder The immune system is not cellular.
Cytokines are proteins that are secreted from intrinsic and acquired immune cells and stimulate and regulate inflammatory and immune responses. Due to the specific biological effects of any cytokine, the deficiency or excess of each of them leads to disease and impairment of the individual’s immune system. It is now possible to evaluate the secretion of cytokines from B and T lymphocytes, such as interferon gamma, TNF-α and interleukin There are two methods of ELISA, radioimmunoassay, a little luminescence, and so on.
MLC (Mixed Lymphocyte Culture)
In this study, if the lymphocytes of two individuals adjacent to the class II antigens are different, each lymphocyte is stimulated and enhanced by other lymphocytes. For ease of perception, the reaction typically disables one specimen under the influence of radiation or some of the substances (as stimulants), and the other as reactants; this is a one-way MLR test. Often, the type of antigen of the stimulant cell is determined and it determines the difference or similarity of the responder lymphocytes.
This test can be used indirectly to evaluate the function of T cells. Flow cyometry is a precise and high-performance method used to identify cells and evaluate their properties. This technique is based on the diffusion of light by the cells tested and the fluorescence emission of them. In this method, monoclonal antibodies of the specific surface molecules of T lymphocytes is used, such as CD2 and CD3 conjugate with fluorescent material (for examination of total T cells), CD4 (T-cell assay) and CD8 (T-cell cytotoxic monitoring).
- Congenital aplasia of thymus (DiGeorge’s syndrome) is a chromosomal abnormality that occurs due to a small deletion in chromosome 22. This deletion occurs in the middle part of the chromosome on the long arm in the 11.2 g area. This disease is one of the most important disorders of T lymphocytes.
Disruption of the parathyroid function leads to less PTH secretion from the gland, causing hypocalcemia and consequent hyperphosphatemia in the children. Cardiac abnormalities, respiratory problems, renal failure, low calcium levels in the blood, decreased blood platelet count, cleft palate (cleft palate), recurrent infections, some advanced autoimmune disorders, such as rheumatoid arthritis, gravicular disease, and delayed growth Development is a symptom of the disease.
- Cutaneous candidiasis is a chronic mucosal infection of mucous membranes, skin and nails, caused by candida albicans. This condition is associated with impaired function of T lymphocytes. The disease is seen in men and women. This disorder may be accompanied by multiple endocrine disorders, such as defective adrenal glands or parathyroid glands, especially Addison’s disease, which is the leading cause of death in these patients.
- Secondary defects in the immune system may be caused by the loss of B or T lymphocytes or their impairment in diseases such as lung cancer, in which cancer cells are replaced by normal cells. So far, the most common cause of secondary immunodeficiency in advanced countries has been the use of chemical drugs to treat cancer. Many drugs are toxic to bone marrow cells and lymphocytes B and T.
- Acquired immune deficiency syndrome is a type of immune system developed by the immune deficiency virus (HIV). The disease caused by the HIV virus has three main stages. In the first stage (acute infection), 2 to 4 weeks after the infection, general weakness and other symptoms appear, all of which recover after 2 to 11 weeks. The second stage of the disease is followed up for a long period without any symptoms (latent period). As the disease progresses, it interferes with the immune system and causes people to develop infections such as opportunistic infections and tumors.
Examining the function of alienation
Phagocytosis is a process in which external particles and germs are surrounded by cell membranes and enter the cell into vesicles, where they are digested by enzymatic mechanisms, etc. In some diseases, such as hereditary agranulocytosis and neutropenia, the number of alienated cells decreases and this causes the disease. In such cases, the complete and differential counting of blood cells will be helpful in diagnosis. At present, there are more simple tests that evaluate the metabolic process associated with phagocytosis to evaluate the function of alienation.
Chronic granulomatous disease (CGD) is a primary disorder of the immune system, in which intrinsic immune phagocytes have defects. Patients with CGD have a high sensitivity to severe bacterial and fungal infections. The cause of the disease is mutation in one of the genes encoding protein complexes called the phoxid oxidase complex (Phox) or the enzyme NADPH oxidase, an enzyme that produces germicidal oxidation radicals.
CGD is often associated with childhood and is associated with frequent fungal infections and internal cystic fibrosis (which destroys hydrogen peroxide). Due to a defect in the killing of phagocytic germs, T lymphocytes activate chronic and chronic macrophages and cause granuloma.
NBT (Nitro Blue Tetrazolium Test)
Nitrobluterazolium is a colorless, colorful, transparent color that is swallowed by neutrophils when exposed to neutrophils. This substance is recovered in the presence of reactive oxygen intermediates (ROS) inside the cell and converted into a compound called formazone, which is blue-purple. The amount of recovered NBT is proportional to the amount of oxygen radicals produced by phagocytes in the respiratory burst. If the patient’s neutrophils do not have the ability to produce superoxide, this sediment is not observed.
- NBT testing is used to evaluate the oxidative neutrophilic blasts in patients with chronic granulomatous disease (CGD).
- This test also applies to people with frequent infections in the bones, skin, joints, lungs and other parts of the body.
- NBT testing is not reliable for differentiating viral and other infectious bacterial infections due to false positive and false positives.
- Blood containing heparin or EDTA is used for NBT testing.
- After sampling, the sample should be sent immediately to the laboratory.
Test of DHR (Dihydrorhodamine) 123 assay
This test is used to diagnose patients with CGD, to identify X-linked carriers and autosomal recessive CGDs, and to evaluate the activity of NADPH oxidase. The DHR test is a very accurate and sensitive method like NBT. In a DHR test, the fluorescence rate in at least 10,000 cells is examined by a flow cytometer and compared to unstimulated cells, while in the NBT test, phagocytosis is typically found in the percentage of cells with conventional microscopy.
Examining the system’s complement function
This complex is a regular system with more than 20 serum proteins that play a very important role in protecting the body against external factors, such as microorganisms that attack the body, as well as inflammatory lesions. Complex activity depends on the sequential breakdown of the complement components, which reinforces this final response.
Other factors such as C3 and C5,6,7,8,9 exist in all three routes. There are special regulatory proteins that, if they are lacking or lacking, the complement system activity is not done correctly. Examination of the complement system’s system involves evaluating the overall performance of the complement, evaluating the complement components and examining the complex regulatory proteins.
The ELISA method is one of the most commonly used immunoassay methods. The Enzyme-Linked Immunosorbent Assay (ELISA) is a simple biochemical method with a high sensitivity that allows the analysis of a large number of samples simultaneously and quantitatively.
The basis of the ELISA method is based on the antigen-antibody complex. In this method, using unique antibody properties, including its high binding strength to the affinity, and the precise identification of the antigen (Specificity), are used to identify, identify, and measure biomolecules.The concentration of complex regulatory proteins such as C1 inhibitor can be evaluated using the ELISA method. In this method, depending on the type of test, antibody or antigen is labeled by the enzyme.
The first step of Elisa is to cover the solid surface with an antigen or antibody. The most common type of solid phase is ELISA, a 96-house plate, organized in 8 rows and 12 columns, made of polyvinyl chloride (flexible) or polystyrene (non-elastic). Plates have very little difference. The plates are fitted with bottom holes for testing, which is finally measured by measuring the color of the spectrophotometer.
The main feature of the solid phase is that the antigens or antibodies easily connect to the surfaces using the patio absorption. This process is usually called kutting. The binding of most proteins to plastic surfaces is probably due to hydrophobic interactions between non-polar structures and proteins and plastic matrix. The speed of hydrophobic interactions depends on the temperature (the higher the temperature, the faster it is), the high concentration of the protein and the movement of the plate.
Specific spectrophotometers are designed to measure color in the ELISA plates, which are called ELISA Reader. Using a software program on these devices, it is possible to draw curves and determine the amount of non-visible sample easily.
Total hemolytic complex assay 0r CH50 assay
Measuring the hemolytic power of the serum complex helps to diagnose some of the diseases that result from reduced or increased serum complexes. The normal value of the unit serum CH50 unit is not constant and depends on the substances used in each laboratory to measure the hemolytic power of the complement and are standardized. The best use of CH50 is to determine the deficiency of one of the complementary proteins. For example, in a patient with frequent Nysseria infections with C5-9 deficiency, the measurement of C4, C3 will be normal, but the CH50 will be very low.