What is an antibody test? Why it is necessary to test for COVID-19 antibodies and what to watch out for

During routine health check-ups or COVID-19 testing, antibody testing is essential. However, few people know how important the antibody test is? Let’s find out with lassho.edu.vn right away what is an antibody test? Why it is necessary to test for COVID-19 antibodies and what to keep in mind!

Learn about antibodies

What are antibodies? Structure of antibodies

Antibodies are technically called antibodies . These are substances produced in the human body, when harmful bacteria or viruses enter the human body. It helps to kill harmful bacteria and protect the body.

The human body has a strong ability to produce antibodies, which can create high immunity against diseases. Antibodies are made up of white blood cells . When bacteria and viruses enter the body, antibodies bind to proteins or different chemicals to protect the body against disease.

Types of antibodies

Antibodies are classified into 5 types as follows:

• IgA : Where lgA is produced, it fights pathogens there. lgA accounts for 15-20% in blood, colostrum, tears and saliva.
• IgD : This is the least functional antibody, accounting for only 1% of the cell, catabolized rapidly and is easily hydrolyzed by the enzyme plasmin during blood coagulation.
• IgE : Plays a role in acute hypersensitivity reactions and antiparasitic immune mechanisms. Occupies large proportions in the body.
• IgG : An important antibody to mother and baby, crosses the placenta, protects the baby in the first weeks after birth because the newborn baby in the first weeks has an undeveloped immune system. They occur most commonly in blood, colostrum and tissue fluids.
• IgM : Has the function of destroying bad antigens, protecting the body, thanks to the combination with multidimensional antigens (viruses and red blood cells). This is the first layer of immunity synthesized in newborns.

How are antibodies formed?

To form antibodies in the human body must go through complicated stages as follows:

• Equilibrium stage:

First, antibodies are formed during the equilibrium phase, by vascular and extravascular diffusion of antigens. This process happens very quickly. If the antigen is no longer diffuse, this phase is lost.

• Disintegration stage:

The decaying metabolic phase causes the body’s cells and enzymes to metabolize the antigen. The antigen is then captured by other macrophages and phagocytic cells. The duration is long or short will depend on each person’s body as well as the production of different immune substances

• Immune elimination phase:

The immune rejection phase combines the newly synthesized antibodies with the antigens, to form antigen and antibody complexes. They are then phagocytosed and degraded. When the immunosuppression phase is complete, the antibody will persist in the serum.

Roles and functions of antibodies in the body

The role and function of antibodies in the human body is extremely important, it helps people fight diseases and recover quickly by creating immune cells.

In the human immune system, antibodies have 3 main roles as follows:

• Binding to antigens:

Immunoglobulins are able to recognize and bind to a corresponding antigen by means of variable regions. Thereby, neutralizing toxins, preventing the adhesion of these toxins to receptors on the surface of cells and avoiding disorders caused by those toxins. Some viruses and bacteria only cause disease when they attach to body cells.

• Activate the complement system:

Activation of the complement system is an important mechanism to help protect the body when bacteria and viruses invade, because they produce plasma proteins. They will kill bacteria by:

– Punch holes in bacteria.

– Promote phagocytosis development.

– Clearance of immune complexes.

– Release of kinetic molecule.

• Mobilization of immune cells:

Antibodies can bind to immune cells at the immobilized end after binding to the antigen at the modified end. This interaction is of particular importance in the immune response.

Antibodies are capable of binding a bacterium to a macrophage and triggering phagocytosis. At the same time, natural killer lymphocytes have the function of cytotoxicity, lysis of bacteria, and cancer cells attached by antibodies.

Why should you test for antibodies?

Antibody testing is very important for the human body to help diagnose systemic autoimmune diseases. Patients can test through blood, saliva to identify a specific disease that we have.

If the antibody test is positive , you have the disease, but sometimes the antibody test is also uncertain. Antibody tests help confirm who has been infected with the virus .

At the same time, the body has gained immunity to this virus or not and checks the body’s immunity against the virus. If a person has been vaccinated against a certain virus, the test will help you know if the body has antibodies against this disease. In addition, this test also helps people determine the general epidemic situation.

Should I get tested for COVID-19 antibodies? Who should be tested for COVID-19 antibodies?

What is a COVID-19 antibody test?

The COVID-19 antibody test is a blood test to find the SARS-CoV-2 viruses in the test person’s body. At the same time, this test also finds antibodies against the SARS-CoV-2 virus.

From there, carry out screening and isolation of suspected infected people. To confirm whether the person is infected or not, it is necessary to take a test sample (nasopharyngeal or pharyngeal fluid) and re-test by RT-PCR method. IgM and IgG are two antibodies against the SARS-CoV-2 virus, produced after the human body is vaccinated and the person’s body has the disease.

Who should be tested for COVID-19 antibodies?

When you have signs and symptoms of a systemic autoimmune disease, you should be tested for COVID-19 antibodies. Specifically, the symptoms are as follows:

• People who have had COVID-19 in the past.
• People who are being treated for COVID-19.
• People at risk of contracting COVID-19.
• People who have received 2 full doses of COVID-19 vaccine after 2 weeks to 3 weeks .
• Persons who need to test for antibodies as prescribed by a doctor.
• Fatigue, persistent fever.
• Arthritis pain.
• Red rash.
• Hair loss.
• Sensitive to light.
• Muscle pain.
• Numbness of the limbs.
• Inflammation damages many organs in the body.
• Sjogren’s syndrome.

Things to keep in mind before testing for antibodies

Before testing for antibodies, there are a few things you need to keep in mind for accurate results:

• You do not need to fast before the test.
• Do not use the following drugs: Aminosalicylic acid, chlorprothixene, chlorothiazide, griseofulvin, hydralazine, penicillin, phenylbutazone, phenytoin sodium, procainamide, streptomycin, sulfonamide and tetracycline. Because they can give you false positives.
• Steroid-containing drugs can cause false negative test results.
• For systemic lupus erythematosus, antibody testing is not used to monitor disease progression.
• Infections, autoimmune hepatitis, biliary cirrhosis, scleroderma, leukemia,… can give positive test results.
• Please consult a professional doctor for proper implementation, timely orientation.

Reference source: Center for Disease Control of Ho Chi Minh City. Ho Chi Minh City, Labor newspaper, VnExpress newspaper – Updated on 10/10/2021.

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