How immunity is developed?
- July 15, 2020
- Posted by: OptimizeIAS Team
- Category: DPN Topics
Subject: Science and tech
Recent research found that immunity developed by the formation of antibodies against SARS-CoV-2 lasts only a few months, and recovered Covid-19 patients are likely to remain susceptible and could get re-infected.
- The analysis found “a potent” level of antibodies produced in 60% of participants during the peak of their infection; and that only 16.7% retained that level of potency 65 days later.
- While the level of antibodies was at a higher level in patients with severe symptoms, the researchers said it is not clear why antibody response correlates with disease severity.
The immune system was separated into two branches: humoral immunity, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum) and cellular immunity, for which the protective function of immunization was associated with cells.
- Antibodies are proteins made by the immune system to fight antigens, such as bacteria, viruses, and toxins.The body makes different immunoglobulin to combat different antigens.
- Antibodies are like fingerprints that give us evidence that a pathogen (the coronavirus in this case) has caused an infection and that the immune system has responded.
- The antibodies usually remain in the blood for a period of time and quickly activate the immune system when the body is exposed to the pathogen again.
- Some antibodies not only recognise when the pathogen returns, but also protect the body for a lifetime from re-infection, as in the case of measles. However, in the case of seasonal flu, the antibodies give protection for a very small period.
The five subclasses of antibodies are:
- Immunoglobulin A (IgA), which is found in high concentrations in the mucous membranes, particularly those lining the respiratory passages and gastrointestinal tract, as well as in saliva and tears.
- Immunoglobulin G (IgG), are involved in the secondary immune response (IgM is the main antibody involved in primary response). IgG can bind pathogens, like for example viruses, bacteria, and fungi, and thereby protects the body against infection and toxins. Comprising up to 80% of the antibodies found in the human body, IgG is the smallest, yet most abundant human antibody, and that of other mammals. IgG can be found in all bodily fluids, and is the only antibody that can protect a foetus by passing through the mother’s placenta.
- Immunoglobulin M (IgM), is the largest antibody, and it is the first antibody to appear in the response to initial exposure to an antigen. B-cells create IgM antibodies as a first line of defense. Their large size gives them excellent binding avidity, and can pick up trace amounts of infection to mark for recognition by phagocytes. IgM is primarily found in serum and due to its size, it cannot diffuse well, and is found in the interstitium only in very low quantities.
- Immunoglobulin E (IgE), which is associated mainly with allergic reactions (when the immune system overreacts to environmental antigens such as pollen or pet dander). It is found in the lungs, skin, and mucous membranes.
- Immunoglobulin D (IgD), which exists in small amounts in the blood, is the least understood antibody.
- Cell-mediated immunity is an immune response that does not involve antibodies.
- Cellular immunity is a protective immune process that involves the activation of phagocytes, antigen-sensitized cytotoxic T cells and the release of cytokines and chemokines in response to antigen.
- Cellular immunity is most effective against cells infected with viruses, intracellular bacteria, fungi and protozoans, and cancerous cells.