Respon Imun 'Innate & Adaptive' | 'Patomed' Medical Video Competition 2020

Summary

The video explains the body's immune response when exposed to pathogens like viruses or bacteria. It details the roles of innate immunity, which responds immediately with non-specific defenses, and adaptive immunity, which takes over if the pathogen persists. The script covers how immune cells recognize and eliminate pathogens through cellular mechanisms, including phagocytosis and the production of antibodies. It also highlights the differentiation of immune cells, the importance of memory cells for faster responses to recurring infections, and the overall process of immune defense from initial exposure to long-term protection.

Takeaways

• 🦠 The body's immune system activates defense mechanisms when exposed to pathogens, such as viruses or bacteria, to protect against infection.
• 🛡️ The immune response is divided into two main types: innate immunity and adaptive immunity. Innate immunity is the body's first line of defense and acts quickly with non-specific responses.
• 👩‍🔬 Components of innate immunity include barriers like skin, mucosal surfaces, and proteins like lysozymes and interferons. Phagocytic cells, such as neutrophils and macrophages, are also involved.
• 🧪 Innate immune cells use pattern recognition receptors to identify pathogen-associated molecular patterns (PAMPs) on pathogens, distinguishing them from normal host cells.
• 🔬 If the pathogen is not eliminated by innate immunity, the adaptive immune response begins, typically within 12 hours to 5 days post-infection.
• 💉 Adaptive immunity involves specific responses with longer-lasting effects, including antibodies and T cells (T-helper cells and cytotoxic T cells).
• 🧫 Dendritic cells play a crucial role in adaptive immunity by presenting antigens from pathogens to T cells, activating them for targeted responses.
• 👥 The adaptive immune response involves clonal expansion of T cells: CD8+ cytotoxic T cells target infected cells, while CD4+ helper T cells aid in activating other immune cells.
• 🧬 B cells produce antibodies through humoral immunity, which neutralizes pathogens and facilitates processes like opsonization and complement activation.
• 🧠 After an immune response, most effector cells undergo apoptosis, but memory cells remain, providing a faster and more effective response upon re-exposure to the same pathogen.

Q & A

What is the initial immune response when the body encounters a pathogen?

The first immune response is the innate immunity, which is non-specific and acts as the first line of defense. It includes components like interferons, lysozymes, and phagocytic cells like neutrophils and macrophages.

What are the key characteristics of innate immunity?

Innate immunity is non-specific and acts immediately upon infection. It includes physical barriers like skin and mucosal membranes, as well as immune cells like phagocytes, and antimicrobial proteins such as complement proteins and defensins.

What role do natural killer (NK) cells play in immune defense?

Natural Killer (NK) cells patrol the body and directly eliminate cells that show abnormal changes, such as those infected by a pathogen or cancerous cells. NK cells recognize these changes and kill the affected cells to prevent infection spread.

How does the adaptive immune system get activated if the innate immune system fails?

If the innate immune response fails to eliminate the pathogen, the adaptive immune system takes over. This involves antigen recognition by specialized cells like T-helper cells, cytotoxic T cells, and B cells, leading to a more targeted and sustained response.

What are antigen-presenting cells and their function?

Antigen-presenting cells (APCs), like dendritic cells, capture pathogens and present their antigens on the cell surface via MHC molecules to T cells, triggering the activation of the adaptive immune system.

What is the difference between MHC class I and MHC class II pathways?

MHC class I presents intracellular antigens, such as viral proteins, to cytotoxic T cells, while MHC class II presents extracellular antigens to helper T cells, activating the humoral immune response.

What is clonal expansion, and how does it contribute to immune response?

Clonal expansion occurs when T cells or B cells recognize a pathogen and proliferate into large numbers of identical cells. This ensures a robust immune response, with effector cells working to eliminate the pathogen.

What are the functions of cytotoxic T cells in the immune response?

Cytotoxic T cells (CD8+ T cells) kill infected cells directly by releasing enzymes like granzymes and perforins that trigger apoptosis (cell death) in the infected cells.

How do antibodies contribute to pathogen elimination?

Antibodies neutralize pathogens by binding to them, mark them for destruction by other immune cells (opsonization), and activate the complement system to aid in eliminating the pathogens.

What is the significance of immune memory in adaptive immunity?

Immune memory allows the immune system to respond more rapidly and effectively upon re-exposure to the same pathogen. Memory cells, formed during the initial immune response, persist in the body for years and can quickly mount a defense if the same pathogen invades again.