Key Concepts Flashcards
What are CYTOKINES?
messenger molecules (immune regulators)
e.g. Interleukins, Interferons, Colony stimulating factors, Tumour necrosis factors
What are CHEMOKINES?
(chemotactic cytokines) - traffic control
What is CHEMOTAXIS?
Unidirectional movement of cells along a concentration gradient of chemotactic molecules e.g. chemotactic cytokines, products of the complement system, lipid derived inflammatory mediators, microbial products
What is IMMUNITY?
State if protection from pathogens e.g. recognition & response, self vs non-self
When does RECOGNITION occur?
- common molecular patterns on pathogens -(non specific - (natural/innate immunity))
- subtle variations between pathogens - (specific - (adaptive immunity))
What do MEMORY responses do?
Provide long term immunity
What is INNATE immunity?
-present from birth
-rapid initial response (acute inflammatory response)
-Non-specific (PAMPs & DAMPs)
-Phagocytic cells
-Natural killer cells
-Mast cells
-Interferons (IFN-alpha & IFN-beta)
-The complement system
What is ADAPTIVE immunity?
-Develops through exposure to pathogen
-Slow primary response
-Rapid memory response
-Specific
- B & T lymphocytes
INNATE RECOGNITION
-Tissue leukocytes are involved in recognition of microbes
-Leukocytes express PRRs
-PRRs recognise PAMPs = integral to pathogen & common across species
-PRR binding triggers initial activation of innate immune response
-Innate response may lead to an adaptive (specific) response
ACRONYMS
- PRRs - Pattern Recognition Receptors
-PAMPs - Pathogen-Associated Molecular Patterns
-TLRs - Toll Like Receptors
-NLRs - NOD-Like Receptors
-RLRs - Rig-Like Receptors
-CDS - Cytosolic DNA Sensors
-MHC - Major Histocompatibility Complex
Pattern Recognition Receptors Summary
- They are expressed on a range of immune cells
-Interaction with pathogen triggers the initial innate immune response
-They are found on the surface and internal membranes
Cell Killing process
-Neutrophils undergo phagocytosis of pathogens
-Macrophages & DCs also process antigenic material (antigen processing) for recognition by T cells
-Leads to an adaptive specific immune response
What is the initial process of ADAPTIVE IMMUNITY
-Persistent antigens (Ag) move to the lymph nodes (LNs)
-LNs –> site of first adaptive immune response
-LNs are junctions between the blood circulation & drained tissue lymphatic fluids
-Lymphocytes leave blood to enter LNs
-Ag drained from the tissues enter B&T lymphocytes for the first time in LNs
SPECIFIC RECOGNITION (Adaptive)
-Involves B&T lymphocytes
-Cells possess antigen-specific receptors
-One receptor per cell = monospecific
-Antigen(Ag): any material which induces specific responses
-B cells: specific membrane-bound antibodies e.g. immunoglobulins -
-T-cells: T-cell receptors (TCRs)
T-cells
Only recognise processed antigenic proteins expressed on MHC molecules on self-cells
B-cells
Antibodies interact directly with epitopes
EFFECTOR B LYMPHOCYTES
-Following Ag exposure, effector B cells = plasma cells –> produce soluble antibodies
-Antibodies found in the blood circulation & various tissue fluids
-Secreted antibodies bind to Ag (not directly cytotoxic, labels Ag for destruction - recruiting other immune cells)
Effector T Lymphocytes
-Different types of T cells (T-helper cells TH, Cytotoxic T cells Tc, Regulatory T cells T-reg)
-Effector TH cells = major producers of cytokines to enhance immune activity
-Effector TCs = kill abnormal self-cells (virally-infected cells, tumour cells)
EFFECTOR RESPONSE
1.Humoral response - flags antigens for destruction, blocks spread of infection
2.Cell-mediated response - recognition, killing of infected cells
IMMUNOLOGICAL MEMORY
-Central feature of adaptive (specific) immunity leading to life-long immunity to a pathogen
-Develops through exposure to a pathogen
-Involves clonal expansion of specific B&T cells, and memory cells
-Memory response is rapid and aggressive
-Establishing immunological memory is the primary objective of vaccination
CLONAL EXPANSION
-Upon binding Ag, specific B&T cells undergo rapid cell division
-Multiple copies of the Ag-primed cells are formed = clonal population
-Process is driven mainly by T-helper cell cytokines
-Gives rise ton effector B&T cells, and memory B&T cells
INATE IMMUNITY
Non-specific initial rapid response to infection and/or tissue damage
-Triggers an acute inflammatory response
-Quite destructive in nature
-Involves PRRs & PAMPs
ADAPTIVE IMMUNITY
specific immunity - develops on Ag encounter with B&T cells
-Recognises epitopes present on the antigen
-Amplifies & focuses immune responses
-Generates immunological memory
