Module 3: The Immune Response Flashcards
Adaptive immune response stages
-antigen recognition
-lymphocyte activation
-elimination of pathogens or non-self perceived antigens
-apoptosis of immune cell
-establishment of immunological memory
Antigen recognition
-after pathogen has entered body and evaded immune responses
-PAMPs are seen by antigen-presenting cells such as dendritic cells
Lymphocyte activation
-requires series of cellular interactions which lead to T cell and B cell differentiation and clonal expansion
Contraction
-once the pathogen is eliminated, the vast majority of activated lymphocytes undergo apoptosis, and the immune response gradually declines
Memory
-the few adaptive immune cells that survive the contraction phase differentiate into memory cells, when re-exposed to the same antigen, there memory cells proliferate quickly to generate an immune response that is much faster and more robust than the first response to the pathogen
Role of MHC molecules
-display antigenic peptides on the surface of cells, which can then be recognized by the TCR and its co-receptors
Classification of MHC molecules
-MHC class I
-MHC class II
Antigen presenting cells function
-t cells are not able to recognize extracellular pathogens by themselves so they require an intermediate to present them antigens
Professional APCs
-macrophage
-b cell
-dendritic cells
Non-professional APCs
-fibroblasts
-glial cells
-rarely needed for this specific function and normally only for a short period of time
Antigen processing by the exogenous pathway steps
-engulfment
-proteolytic processing
-formation of MHC-antigen complex
-cell surface expression
-recognition by helper T cells
Engulfment
-APCs engulf foreign antigens by endocytosis, forming a endosome
Proteolytic processing
-foreign antigens inside endosome are broken down into fragments
Formation of MHC-antigen complex
-vesicle fuses with vesicles containing MHC molecules, forming MHC-antigen complexes
Cell surface expression
-MHC-antigen complex is transported to the plasma membrane, where it will be displayed on the surface of the cell
Recognition by helper t-cell
-t cell receptor on surface of helped t-cell binds to the MHC-antigen complex on the cell surface of the APC, which will initiate an adaptive immune response
Lymphocyte activation
-mediates efficiency of the specific immune response
-macrophages
-dendritic cells
-b-cells
-helper t cells
-cytotoxic t cells
Cytokine networks
-balance humoral and cell-mediated immunity
-chemokines
-interleukins
-interferons
-tumor necrosis factor
-growth factors
Steps of T cell dependent B cell activation signalling pathway
-peptide-MHC class II complex
-signal 1: TCR-peptide:MHC complex
-expression of co-stimulatory molecules
-signal 2: co-stimulation
-signal 3: cytokines
-outcome of 3 signals
Immune synapse structure
-interaction between a T cell and APC
Immune synapse function
-effective activation of T cell
-synapse holds signal proteins together to form stronger connection
Memory B-cells
-memory occurs when there is a second encounter with an antigen
Natural passive immunity
-acquired by fetus or newborn
-short lived immunity
-no immunological memory
Artificial passive immunity
-acquired by injection of serum containing antibodies
-immunity is temporary
-no immunological memory
Natural active immunity
-acquired through infection by a pathogen
-immunological memory has a significant chance of being developed
Artificial active immunity
-acquired through vaccination
-no symptoms present
-immunological memory has a significant chance of being developed
Clonal expansion
-production of large quantity of identical cells from the same original cell
Interferons
-induce antiviral state by inhibiting replication of viruses
Interleukins
-regulate immune and inflammatory responses by affecting proliferation and differentiation of immune cells
Tumor necrosis factors
-implicated in tumor regression and systemic inflammation which can lead to septic shock
Chemokines
-call in cells to the region of infection or injury and play a key role in inflammation, immune responses and hematopoiesis.
Growth factors
-stimulate growth, proliferation, healing, and cellular differentiation
MHC class 1
-on every cell except red blood cells
-bodies way of telling cells that everything is okay
-if cell is infected, the news will be displayed on MHC class 1
MHC class 2
-on B cells, macrophages, dendritic cells etc
-bodies way of telling cells that something weird is floating around that needs to be attended to
-induces CD4 cells
