Immune Deficiency 1a - Immune responses Flashcards
Purpose of the Immune System?
- detect, respond and eliminate pathogens
- maintain tolerence to self, environmental antigens and paternal pregnancy antigens
- induce memory to perviously encountered infection
- Restore organ/tissue homeostasis (resolution of inflammation, repair injury)
Type of Immune responses to cell death vs cell stress?
- Cell death/damage → Microbial PAMP/Host DAMP → Type 1 + 3 immune response (Th1 and Th17)
- Cell Stress/ Tissue ‘pertubation’ → Host DAMP > Microbial PAMP → Type 2 Response (Th2)
Differences between Innate and adaptive immune system, and how they interact?
Innate :
- Rapid onset
- Germ line receptor to detect molecular structure of pathogen
- pathogen recognition is contact dependant on tissue damage and effector
Adaptive :
- Slower
- somatic reattachment of T and B cell receptor to recognise microorganism
- requires accessory signals (cytokines etc.)
Which Cytokines are made by CD4 Th1 cells, and what are their effectors?
these are Type 1 response
IFN -Y
TNF-Alpha
IL2
on Macrophages and CD8
Which Cytokines are made by CD4 TH17, and effectors?
Type 3 Response
IL 17 & 22 on Neutrophil and Epithelial Cells
Which Cytokines are made by CD4 T follicular cells, and effectors?
IFN-Y
IL17- A
IL-4
IL-21
On germinal centre B cells to promote class switching and antibody response.
Role of Dendritic Cells?
integrate lots of different responses and pathogen classes to induce distinct cell mediated immune responses
Type 1 Immune Response?
Against Intracellular pathogens e.g. TB and Viruses
- Dendritic Cells release INF-Y and IL12 to cause CD4 cells to differentiate into CD4 Th1 cells
- interferon gamma release causes activation of CD8 T cells and macrophages - DC act on B cells and T follicular helper cells
- CD4–CD40L cross linking on GC B cells and CD4 TFh1 cells cause class switching to make B cells that produce IgG preferentially to IgA
Type 3 Immune response?
Against Extracellular Bacteria and fungi (HiB, Pneumococcus, candida)
- DC -> IL6 etc. Causes CD4 Th17 cell to release
a. IL 17 - act on neutrophils
b. IL 22 - boosts epithelial cell defenses - IL 6 and 21 - same as Type 1 with class switching but IL 21 preferentially makes IgA
Type 2 Immune Response
**against ticks and parasites **
- DC cell : IL 4 activates CD4 cell into Th2 cell.
- release of IL 4, 5 and 13 on basophils, eosinophils and mast cells - DC bind to B cell and release IL 6 and 21, TFh2 cell binds to B cell causes class switch to IgE
Types of B cells : Innate like B Cells?
Spontaneous IgM Production, almost innate immune system
Types of B cells : Marginal Zone B Cells
specialized in responding to blood-borne pathogens and participate in the initial immune response to these pathogens, particularly those encapsulated with polysaccharides
- T cell independant
- IgM > IgG/IgA
- limited memory and antibody affinity
- found in spleen and GI tissue
Types of B Cells : Extra-follicular B cells
activated B cells that differentiate into antibody-secreting plasma cells outside the germinal centers. They are primarily involved in responding to T-cell-independent antigens and generating an initial rapid antibody response
- Rapid production, class switch
- exhibit memory
-short lived
Types of B Cells : Germinal Centre B cells
central to the adaptive immune response. They are formed within germinal centers of secondary lymphoid organs, like lymph nodes and spleen
- T cell dependant
- take 5-7 days for production
- class switch
- memory
- affinity maturation
-long lived plasma cells
Immunoglobulin Structure?
2 Heavy and 2 Light Chains with 2 functional units:
1. Fab : binds to antigen
2. Fc : Effector Fucntion
What specifies antibody isotype?
Heavy chain
