- What are centroblasts, centrocytes, immunoblasts, and plasmablast (8)
- Centroblasts: Activated B cell, enlarged, rapidly proliferating in the germinal centre of a lymphoid follicle
- Centrocytes: Non-dividing progeny of centroblasts
- Immunoblast: Lymphocyte that has been activated by an antigen, that further undergoes clonal expansion
- Plasmablast: precursor of plasma cell that is derived from an antigen-presenting B cell that has been activated and proliferated
- Briefly describe the effectors of innate immunity under the following: Cellular effectors, Non-cellular effectors
- Cellular effectors
- Granulocytes:
- Eosinophils: Allergic reactions, Helminth infections
- Basophils: Allergy
- Neutrophils: Acute inflammation
- Natural Killer cells: Immune-surveillance
- Mast cells: Allergic reactions
- Macrophages and Dendritic cells: Antigen presenting cells
- Granulocytes:
- Non-cellular effectors
- Physical barriers:
- Skin and mucous membranes: Tight junctions, ciliary function, symbiosis with microorganisms, MALT
- Coughing and sneezing reflex
- Biochemical barriers:
- Body secretions: Lactoferrin, Lysozyme, Acid Hydrolysase, RNAses, Defensins, Acids
- Exocytosis of cytotoxic molecules and proteins: Major basic protein, Superoxide, Hypochlorite, Hydrogen peroxide, Hydroxyl radicals, Nitric oxide
- Humoral defenses
- Acute phase proteins: Hepcidin, C-reactive protein, transferrin
- Complement proteins: Bind to Fc complement binding portion on Immunoglobulins, Lectin or antimicrobial surfaces
- Physical barriers:
- Cellular effectors
What are the differences between the key features of the Innate and adaptive immunity
| Innate immune system | Adaptive immune system | |
|---|---|---|
| Key components | Physical and Biochemical barriers, Complements, Antigen presenting cells, Granulocytes, NK cells | B cells, T cells, Immunoglobulins |
| Genetics | Germline encoded. Does not change over the course of a lifetime. | Encoded as V(D)J recombination and hypervariation |
| Inheritance | Inherited | Not inherited |
| Response time | Fast – within minutes to hours | Slower – longer gap between antigen exposure and full effect |
| Specificity | Non-specific | Highly specific. Constant expansion over time. |
| Memory response | Absent | Present. More potent and faster after subsequent antigen exposure |
| Effector proteins | Lysozyme, Defensins, Cytokines, Complement, CRP | IgA, IgM, IgG, IgD and IgE. Bridges the innate and adaptive immune system. |
| Receptors | Pattern Recognition Receptors | T-cell and B-cell antigen specific receptors |
- Innate and specific immunity play a complementary role in microbial protective immunity . Discuss the statement (5)
- Antigen presenting cells (Macrophages and Dendritic cells) activate T-cells
- Cytokines secreted by T-cells upregulate Acute phase reactants (IL-6) and activate innate immune cells (Macrophages via IFN-y)
- Antibodies activate complement cascade
- Antibodies act as opsonins for neutrophils
- Antibodies facilitate Antibody-dependent-cell-cytotoxicity (ADCC) by NK cells
- Describe the mechanisms by which extracellular bacteria cause disease and the specific immune responses involved (5)
- Colonization**:** Acute inflammation
- Antigenic variation: Antibody production
- Intracellular survival: Phagolysosome killing by Macrophages
- Bacterial nutrition: Lactoferrin denies bacteria Iron
- Inflammatory response: Bacteria contained within granulomas
- Inflammatory response
