How The Body Reponds To Infection Flashcards
Major success of vaccination
Worldwide eradication of smallpox
Types of infectious agents
Viruses; Bacteria; Fungi; Protozoa; Worms;
White blood cells
Leucocytes
Secreted mediators of immunity:
Antimicrobial:
Regulatory/inflammatory:
Antibodies/immunoglobulins;
Complement proteins;
Cytotoxins;
Interferons;
Cytokines (interleukins, interferons);
Histamine;
Chemokines;
Lymphocyte are produced and developed in?
They congregate in?
Afferent and efferent lymphatics
Primary lymphoid organs (bone marrow and thymus) and then recirculate around the body in the blood;
Specialised lymphoid tissues - spleen, lymph nodes, mucosa-associated lymphoid tissue (MALT);
Lymphocytes enter the spleen from the blood and then return directly to bloodstream;
Most lymphocytes that enter the lymph nodes do so directly from the blood but some diffuse into other tissues and drain to lymph nodes via the afferent lymphatics. Lymphocytes return to blood stream by lymph node by efferent lymphatics, with most entering the blood at the thoracic duct;
Major functions of immunity
Recognition -interaction with microbes and their components;
Defence - elimination of microbes and their products;
Innate immunity
Quickly activated;
Remains the same with repeated exposure to same microbe;
Moderate efficiency;
General response to categories of microbes;
Recognition of pathogen-associated molecular patterns (PAMPs) - eg. Viral double-stranded RNA;
Recognition by pattern recognition receptors (PRRs) - eg. Toll like receptors;
Eg. Macrophages
Adaptive/acquired immunity
More slowly activated;
Improves on repeated exposure to same microbe;
High efficiency;
Specific response tailored to individual microbes;
Recognition of antigens specific to each type of microbe;
Recognition by antigen-specific receptor clonally expressed by lymphocytes;
Eg. - lymphocytes
Stages of a primary immune response
- Microbes penetrate the surface epithelial barriers (eg. Epidermis of Skin);
- Immediate local immune response (innate);
- Early immune response (innate/inflammatory)-inflammatory mediators from complement, macrophages, mast cells - attract leucocytes and serum proteins (more complement);
- Later adaptive response - antigen carriage from site of infection by dendritic cells to lymphoid tissue; specific activation of T and B lymphocytes and Ab production recirculation to site of infection;
- Memory T and B cells give faster and bigger responses on second exposure to same infection (stage 4);
Immune strategies for different categories of infection
Extracellular -
Complement proteins;
Phagocytes;
Antibodies;
Intracellular -
Helper T cells;
Intracellular cellular cytosolic -
Interferon proteins;
NK cells;
Cytotoxic T cells;
Immunopathology
Diseases involving defects in or inappropriate activity of the immune system;
Types - Immunodeficiency; Allergy; Autoimmunity; Transplant rejection; Lymphoproliferative diseases;
Immunodeficiency disorders
Particular components of immune system missing or defective;
Primary immunodeficiencies - genetic disorders;
Secondary immunodeficiencies - acquired later in life (AIDS due to infection with HIV that kills helper T lymphocytes);
Allergies
Inappropriate adaptive immunity against non infective environmental material (allergens) that leads to inflammatory tissue damage.
Eg. Allergic rhinitis - hayfever caused by plant pollen;
Asthma - caused by house dust mite proteins;
Eczema;
Anaphylaxis;
Contact dermititis - eg. Nickel allergy
Autoimmunity
Adaptive immunity is directed against certain of the body’s own components (autoantigens);
Eg. Autoimmune thyroiditis;
Rheumatoid arthritis;
Systemic lupus;
Transplant rejection
Rejection of transplanted tissue grafts which is a man-made form of immunological tissue damage caused by antigenic differences in tissue components between donor and recipient that generate an adaptive anti-graft immune response by the recipient;
