Specific Immune Response

• Antibody


  A protein that acts against a specific antigen.

  
• 4 things antibodies do

  Agglutination, anti-toxins, neutralisation, opsonisation
• Agglutination


  Antibodies can cause pathogens carrying antigen-antibody complexes to stick together. This helps to prevent them spreading around the body and makes it easier for phagocytes to engulf them.
• Anti-toxins


  Some antibodies work by neutralising toxins produced by pathogens.
• Neutralisation


  Some pathogens invade cells. Antigens stick on, making an antigen-antibody complex. Once a pathogen is part of this complex, it can no longer invade our cells.
• Opsonisation


  The antibody of the antigen-antibody complex acts as an opsonin, which in turn tags the pathogen and highlights it, so it's more easily engulfed.
• Specific immune response


  Detects, recognises and attacks specific microorganisms. It maintains an immunological 'memory' of previous infections. It involves lymphocytes known as B cells and T cells which have specifically-shaped receptors on their cell surface membrane.
• Where do B cells/B lymphocytes originate from?

  Stem cells in bone marrow and they mature in the bone marrow.
• Main types of B lymphocytes

  Plasma cells

  B effector cells

  B memory cells
• Plasma cells


  Produce antibodies. They only last a few days but produce approximately 2000 antibodies per second while active.
• B effector cells


  Divide to form plasma cell clones. This allows you to mass produce the right plasma cell.
• B memory cells


  They live a very long time and are programmed to remember specific antigens for recognition to trigger a secondary immune response.
• Where do T cells originate from?


  Originate from stem cells in bone marrow and are matured in the thymus gland.
• Main types of T lymphocytes


  T killer cells, T memory cells, T helper cells, T regulator cells
• T killer cells


  Destroy pathogens by producing perforin.
• Perforin


  a protein, released by killer cells of the immune system, that destroys targeted cells by creating lesions like pores in their membranes.
• Opsonin

  Antibody or complement protein that encourages phagocytosis
• T memory cells

  Live a very long time. They're programmed to remember specific antigens for recognition to trigger a secondary immune response and can rapidly produce T killer cells.
• T helper cells

  Have CD4 receptors on their cell surface membrane. They can bind to antigen presenting cells (APCs) and produce interleukins. Interleukins can signal more T helper cells (THCs) or T killer cells (TKCs) to the area of infection or they trigger a B cell to become active in a humoral response.
• Antigen presenting cells

  dendritic cells (APCs in the skin), macrophages, B cells
• Humoral immune response

  The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies, which defend against bacteria and viruses in body fluids.
• T regulator cells


  Suppress the immune system once the pathogen has been eliminated. Also ensures the body's antibodies don't attack their own antigens which can lead to an autoimmune disease. Interleukins are important in this control.
• Cytokine


  Cell signalling molecule. Interleukins are a type of cytokine.