Decoding Your Body’s Defense: How You Fight the Flu

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Fighting the Flu: How Your Body Defends Against Influenza

Influenza, also referred to as the flu, is a respiratory infection that is extremely contagious and is caused by influenza viruses. While fever, coughing, and weariness are the typical symptoms of a moderate sickness brought on by influenza, some people may develop severe symptoms that require hospitalisation or even result in death. Fortunately, the innate and adaptive immune responses provide our immune system with a two-pronged defence against this unwanted guest.

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The Initial Defence: The Innate Immune System

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Consider the innate immune system as the safety net of your body. It’s a general defence mechanism that activates the moment any pathogen, including influenza viruses, is encountered. This is how it addresses the flu:

• Physical Barriers: The skin, mucus, and tears serve as the body’s initial line of defence, keeping the virus out of the body.
• Chemical Warfare: To prevent virus replication, interferons and other antiviral chemicals are produced by the epithelial cells lining the respiratory system.
• Inflammatory Response: Infected cells release cytokines, which are inflammatory chemicals that cause inflammation, when the virus penetrates these barriers. In order to stop the spread of the virus, this raises blood flow to the affected area, bringing immune cells and causing a fever.
• Defenders of the Cell: Phagocytes, such as neutrophils and macrophages, engulf and kill virus-infected cells. Natural killer (NK) cells, on the other hand, recognise and destroy contaminated cells directly.

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Despite its speed, the innate immune response is not flawless. All it can do is delay the virus’s spread, giving the more focused adaptive immune system more time to mature.

The Developing Specificity of the Adaptive Immune System for Durable Protection

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The adaptive immune system is more selective yet operates more slowly. Although it takes a few days to completely function, it provides long-term defence against recurrent infections with the same influenza strain. This is how it operates:

• Presentation of Antigens: When a virus infects a cell, specialised antigen-presenting cells (APCs), such as dendritic cells, engulf the infected cell and fragment the viral protein (antigens). Following that, these antigens and molecules known as MHC (major histocompatibility complex) are shown on the surface of the APC.
• Activation of B and T Lymphocytes: Active B and T lymphocytes constantly search the body for these antigen presentations. A B or T cell is activated upon identifying a particular antigen fragment on an APC.
• B Cells and the Production of Antibodies: Activated B cells undergo differentiation into plasma cells, which produce vast amounts of antibodies that are highly specific to the influenza virus. By binding to the virus, these antibodies aid in its removal and stop it from infecting healthy cells. We refer to this particular type of antibody response as humoral immunity.
• T Cells and Cellular Immunity: Helper T cells (Th cells) and cytotoxic T lymphocytes (CTLs) are the two primary subtypes of activated T cells. Th cells aid in the activation of B cells and other immune cells, which further enhances the immune response, while CTLs kill virus-infected cells directly. Cellular immunity is the targeted attack on infected cells.

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Within the adaptive immune response, memory B and T cell growth is an essential component. Even years after the initial infection, these memory cells are still on guard. The body can effectively avoid re-infection or greatly lessen the severity of disease if memory B cells and memory T cells swiftly create specific antibodies and mount a cellular response in the event that the same influenza strain re-enters the body.

Immune Response and Immunopathology: The Tightrope Walk

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An overly enthusiastic response to influenza can occasionally be harmful, even if the immune system’s response is necessary for the virus to be eliminated. Pneumonia and other consequences can result from the innate immune system’s inflammatory response, which damages healthy tissues. Furthermore, an overabundance of T cells may occasionally be a factor in lung damage.Fight the Flu

Final Thought: Cooperating for the Best Defence

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Together, the innate and adaptive immune systems fight influenza infection. The adaptive immune system has more time to formulate a focused attack because of the innate system’s quick, non-specific reaction. By comprehending the interplay between these systems, we may devise tactics such as immunisation to enhance our inherent defences and reduce the severity of influenza. Vaccination lowers the chance of serious sickness and complications by exposing our immune system to the influenza virus in a controlled environment, which helps it form memory cells and get ready for a future infection.