Public: Innate Immunity Flashcards
Give 2 instances when the immune system can be beneficial
Protection from invaders
Elimination of altered self
Give 2 instances when the immune system can produce a detrimental effect
Discomfort (inflammation)
Damage to self (autoimmunity)
Describe the innate immune system
first line of defence
rapidly invoked
non-specific
Name 4 Innate mechanisms
- Anatomic resisting barriers (skin, mucous)
- Physiologic barriers (temperature, pΗ, etc)
- Phagocytosis
- Inflammatory defensive barriers (vasodilation, increase in capillary permeability, influx of phagocytes)
Name 3 ways the epithelia has innate immunity
physical barrier to infection
Killing of microbes by locally-produced antibiotics
Killing of microbes and infected cells by intraepithelial lymphocytes
Name 4 soluble factors of the innate immune system
Lysozymes
Acute phase proteins
Complement
Interferons
What do lysozymes do?
Split the bacterial wall of susceptible bacteria
What do acute phase proteins do?
Opsonisation
Attraction of phagocytes
Increased blood flow
What does complement do?
Opsonisation
Define opsonisation
Antibody opsonization is the process by which a pathogen is marked for ingestion and eliminated by a phagocyte. ..
What do interferons do?
Antiviral resistance
2 types of cells involved in the innate immune system and what they do
Phagocytes (macrophages) - engulf particles
Natural killer cells -recognise cell surface changes occurring on virally infected and tumour cells (cytotoxicity)
Cells of the immune system family tree
Two main groups
Myeloid cells
Lymphoid cells
Cells of the immune system family tree
2 groups under myeloid cells
Granulocytic
Monocytic
Cells of the immune system family tree
3 types of Granulocytic cell
Neutrophils
Basophils
Eosinophils
Cells of the immune system family tree
4 types of Monocytic cells
Macrophages
Langerhans
Kupffer cells
Dendritic cells
Cells of the immune system family tree
2 groups under lymphoid cells and everything under them
T cells - T helper and T cytotoxic
B cells - plasma cells
Draw the myeloid lineage on whiteboard
and check slide 11 to see if you’re right
Describe monocytes
The human blood monocytes are larger cells than lymphocytes; they usually have a horseshoe-shaped nucleus and often contain faint azurophilic granules.
Macrophages
They are often referred to as scavengers or antigen-presenting cells (APCs). Stimulated macrophages exhibit increased levels of phagocytosis.
-Phagocytosis, intracellular and extra-cellular killing, tissue repair, antigen presentation for specific immune response.
Neutrophil
The most important cellular components in bacterial destruction. They are relatively large and most abundant white blood cells with lobed nucleus and cytoplasmic granules (lysosomes).
PMN granules are of two kinds: Primary and Secondary
Phagocytosis steps
1) Binding
2) Internalisation in vacuole
3) Fusion of vacuole with lysosome
4) Digestion of bacteria
5) Exocytosis
Basophils
They are found in a very small number in the circulation and are characterised by deep violet-blue granules.
- Active in allergic reactions
- Release histamine
- Bind complement C3a, C3b & C5a
Eosinophils
Eosinophils gather wherever there is a parasite infection or an allergic reaction such as allergic asthma, and then release their toxins contained in their granules. They can be triggered to degranulate by appropriate stimuli.
They play important role in the defence against parasitic infections.
Allergic reactions
-Histamine release
NK cells
Natural killer cells
Kill infected cells and also phagocytosed microbes
Mast cells (concentrated under the body surfaces) mechanism of action
Release factors which increase blood flow and vascular permeability bringing components of immunity to the site of infection
Neutrophils and macrophages (phagocytes)
Engulf (phagocytose) and destroy micro-organisms
Eosinophils
Secrete factors which kill protozoa and worms
Natural killer cells
destroy virus infected cells
Alternate pathway of complement (a system of enzymes and control proteins)
Activate mast cells, attract phagocytes, make micro-organisms more easily recognised by phagocytes (opsonisation), lyse micro-organisms
Acute phase proteins (C-reactive protein, Mannose-binding lectin)
Activate complement and opsonise
Cytokines - interferon
toxic to viruses
Give an example of an organism resistant to phagocytosis
and its mechanism
Pneumococcus
Capsular polysaccharide inhibits phagocytosis
Give an example of an organism resistant to reactive oxygen intermediates in phagocytes
and its mechanism
Staphylococci
Production of catalase, which breaks down reactive oxygen intermediates
Give an example of an organism resistant to complement activation
and its mechanism
Neisseria meningitides - Sialic acid expression inhibits C3 and C5 convertases
And
Streptococcus - M protein blocks C3 binding to organism and C3b binding to complement receptors
Give an example of an organism resistant to antimicrobial peptide antibiotics
and its mechanism
Pseudomonas
Synthesis of modified LPS (Lipopolysaccharide) that resists the action of peptide antibiotics
