Lecture 5 Immunity and disease Flashcards
What is immunity?
Protection/defence against infections. Bacteria, virus, fungi, toxins, cancer.
What does immune system do? (3)
Distinguishes self from non-self molecules. Activates mechanisms to either eliminate or neutralise threat. Innate and adaptive.
Define innate immunity?
Defence mechanisms present before infection.
Examples of innate immunity?
Skin, mucus membranes, phagocytic cells, inflam, fever
What phagocytic cells are in the innate immunity?
Neutrophils and macrophages.
What is the time frame for the innate immunity?
0-12 hours
Complement and NK cells are in which immunity?
Innate
What does the adaptive immune response entail?
Cell-mediated immunity and humoral immunity
What cells are involved in the adaptive immunity?
B lymphocytes and T tymphocytes
What do B lymphocytes become?
Antibodies
What do T lymphocytes become?
Effector T cells
Name 4 examples of non-specific deferences?
Intact skin, mucus, cilla and chemical barriers
How does skin defend?
Mechanical barrier. Keratin outer layer. Dead cells constantly lost -> X invading bacteria colonisation.
What does sweat and oils contain?
Anti-microbial chemicals
How do mucous membranes defend?
Normal flow of mucus washed bacteria and viruses off membranes. Cilia in resp tract, acid in stomach and vagina. Enzymes in saliva & eyes
How do chemical barriers protect?
Proteins. Complement (work with other defence mechanisms). Interferons (X replication of viruses)
What do cellular defences involve?
Phagocytosis
What are granulocytes?
Neutrophils, Eosinophils and Basophils
How do granulocytes work?
Remove dead cells and micro-organisms
What attracts granulocytes?
Inflam response or damaged cells
What are monocytes?
Macrophages
Monocytes/macrophages location?
in tissues which act as filters for trapping microbes
Monocytes/macrophages life span?
Live longer than granulocytes
Do monocytes or granulocytes arrive at site first?
Granulocytes
What do monocytes/macrophages do?
Stimulate specific immune response (antigen presenting).
What are the non-specific responses to infection?
Macrophages releasing IL-1 & IL-6, fever, pain, swelling, redness, acute-phase proteins.
Why does a fever work?
Most bacteria grow optimally at temp below body temp
Why does pain, swelling and redness work?
^ capillary permeability, ^blood flow, ^ phagocytic.
Why does acute-phase proteins release from liver work?
Bind to bacteria and activate complement proteins
What is the specific immunity?
Adaptive. Needs antigens and lymphocytes
What are antigens?
Toxin/foreign substance which induces immune response.
How much of lymphocytes are carried in blood? Where are the rest?
1%. Rest in lymphatic system.
How many lymphocytes in human body?
2x10^12
What is a lymphocyte?
small leucocyte (white blood cell)
Where do B-cells mature?
Mature in bone marrow then conc in lymph nodes and spleen
Where do T-cells mature?
Mature in thymus
Both B-cell and T-cells
Circulate in blood ensuring they come in contact with pathogens
What do T-cells recognise?
X free antigens. Only recognised antigens presented by major histocompatibility complex - Class I (all cells) class II (APC)
What do T-cells do?
Directly attack invaders (cytotoxic, CD8+, MHCI) and recognise pathogens inside cells.
What can sometimes recognise and destroy cancer cells?
Cytotoxic T-cells
What to T helper cells do?
Stimulate B-cells and activate cytotoxic cells/macrophages.
How do T-cells recognise an invader?
Detect an antigen - protein marker on cell surface.
Define epitope?
Fragment of antigen
What happens when an antigen is encountered by macrophage?
It will bring the protein to a helper T-cell -> if T-cell recognises it as “not-self” -> Launch immune response.
How are B-cells stimulated to divide?
Helper T-cells (CD4+) that has been stimulated by antigen -> releases cytokines to stimulate B-cell division.
How does HIV affect immune response?
Destroys helper T-cells so immune response diminished
What do B-cells do?
Secrete antibodies, humoral immunity and recognise pathogens outside cells.
What antibodies do B-cells produce?
Glycoproteins, specific, hypervariable region, different subtypes (IgM, IgA and IgD)
Antibodies are on
B-cells
B-cell antibodies can be
Glycoproteins, specific hypervariable region, or different subtypes
What different subtypes of antibodies is there?
IgG, IgM, IgA, IgD.
Define opsonisation
identifying the invading particle to the phagocyte
B-Cells also stimulate
Complement
What do memory cells do?
remain ready to divide rapidly if an invasion occurs again
Explain pathway of B-cells
Antigen binds to antibodies-> B-cell multiples-> differentiate into 1) memory cells 2) plasma cells - more antibodies
Examples of when immune system is deficient?
Chemo, HIV, Splenectomy, bone marrow dysfunction
What is HIV?
Human immunodeficiency virus. Retro virus.
How does HIV effect?
Infects CD4 + T-cells. Infection -> latency -> AIDS (acquired immunodeficiency syndrome).
What is AIDs?
Acquired immunodeficiency syndrome. Decline in CD4 and T cells -> opportunist infections.
Causes of 2nd immunodeficiency?
Malnutrition, burns, uremia, diabetes m, recreational drugs and alcohol. AIDs!
Type 1 hypersensitivity examples?
Anaphylaxis/allergy. Rhinitis (hayfever)
Self reactive lymphocytes are
deleted centrally and suppressed in periphery
4 examples of autoimmune diseases
Hashimoto’s thyroiditis, type 1 diabetes M, coeliac disease, multiple sclerosis,
Example of live (attenuated) vaccine?
MMR
Example of inactivated vaccine
Hep B
Example of toxoid (bacterial toxin) vaccine?
Diptheria
Example of conjugated (antigen linked to protein) vaccine
pneumococcal
