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Natural and Adaptive Immunity (Natural Immunity (Innate) (Has complement…
Natural and Adaptive Immunity
Natural Immunity (Innate)
First and second line defence
Made up of
Physical components
Epithelial cells joined by tight junctions - In skin , gut, lungs eyes/nose
Longitudinal flow of air/fluid - In Skin and Gut
Movement of mucus by cilia - In Lungs
Cellular components
Fatty acids- in skin
Low pH and enzymes - In gut
Salivary enzymes - eyes/nose
Antibacterial peptides - In Skin, Gut, Lungs
Non-cellular or particulatecomponents
Normal flora - in skin , gut
General mechanism (non specific)
Secrete
Cytokine
-In response to stimulus, has specific effect on cells interaction
Types
Interleukins
B-lymphocite proliferating stimulator
Lymphokines
cell signal molecules
Tumor necrosis factor
mediate acute inflammation
interferons (trigger inflammation and respond to infections)
Host specific but not pathogen specific
Present since born
Functions
Early steps in entry restriction of pathogen
Induce further immune response
Has complement System
Complement antibody ability and phagocytic cells to clear pathogen
Has 3 pathways
Classical Pathway
Starting: C1 and C2 with activation from antigen-antibody
Alternative pathway
Starting : required preformed C3b
Lectin pathway (Mannose-Binding Lectin (MBL) pathway)
Starting; initiated by binding of MBL to mannose containing CHO on bacteria or viruses
3 steps process
1) Recognition
2)Enzyme activation
3)Expression of biological activities
Importances
Trigger inflammation
attract phagocytes to infection site
Lysiss of gram(-) bacteria/virus
activation of B-lymphocyte
Remove harmful immune complexes from body
Adaptive Immunity
Third line of defence
Two major types: Naturally occuring
Humoral Immunity
Involves B cell and production of antibody
Antibodies production:
T- Cell dependent
Antigen fragment bound to unique MHC molecules
This complex attracts T cell
Antigen fragments displays on surface of B cells
T cell secretes Cytokine that help B cells to multiply and mature to become plasma cells that produces antibodies
B cells engulfs antigen & digests it
T-Cell independent
Do not require involvement of T cells
Type
Type 1: Polyclonal = several specificiities activation
Type 2: Macrophages present several of the same antigen in way that causes cross linking of antibodies on the surface of B cells
Steps on how B cells recognize and attack foreign substances
Antigen Recognition
:check: B cells recognize via membrane bound antibodies
Antigen elimination
:check:Perform by antibodies
:check: Mechanism use include Neutralization, Opsonization and Phagocytosis, & Activation of complement
Memory
:check: After initial response, memory cell pools is produced so that higher production of antibodies can be produced during second response.
Differentiation
:check:After a clone of B cells activated :
a. Cells divide ( :arrow_up: in no. means enough cells to mount an effective response)
b.Cells differentiated :arrow_right: Plasma cells :arrow_right: Produces/ Secretes antibodies (specific to the antigen)
Clonal selection
:check:Antigen encounter selects cells and induce to proliferate to form clone of effector cells
Cell-mediated Immunity
Production of cytotoxic T-cell
Activation of Macrophages, Natural Killer Cell and Cytokine mediated by T-cell
Production of effector T-cells from naive T-cells
Form peptide: MHC complex on the surface of antigen presenting cell (APC)
Production of effector T-Cells
Has three functional class( Effector T-Cells)
Peptides from intracellular pathogens that multiply in cytoplasm
Carried by MHC Class 1, Presented to CD8 T-Cells
Differentiate to cytotoxic T-Cells that kill infected target cells
Peptides antigens from pathogens multiplying in intracellular vesicle & those derived from ingested extracellular bacteria and toxins
Carried by MHC Class 2, Presented by CD4 T-Cells
Two types of effector cells produce:
2 more items...
Encounter specific antigen
Specific mechanism
Two types:Artificially Acquired
Active : Vaccine
Stimulating the immune system to attack the foreign substance
Suspension of weakened/ killed pathogens /toxin/antibodies/lymphocytes that is administered primarily to prevent disease
Given through
Injection
Oral
Administered to Mucosal surface
Passive: Serum
Immediate antibody protection
Antibodies produced by other animal or person that have been actively immunized
Infusion of serum / plasma containing high amount of antibodies
The recipient never produced the same antibodies
The recipient only temporary benefit from te antibodies as long it persist within the body
Connection between this two immunity
Communication involves cell to cell interaction
Antigen-presentation complex (APC)
Soluble molecules
CYTOKINES
Produce by cells in response to pathogens
neutrophils
monocytes
macrophages
mast cells
dendritic cells
i.e. Interleukin (IL) ; IL-1, IL-6
Can act on many different cellular targets
Dendritic cells
Detect phatogens
activate innate response
Phagocytosis
Activate T cells
Send signals to B cells
production of antigen-specific antibodies
Carry out phagocytosis
Found in tissues ; lymph nodes, skin, muscosal surfaces
Immature cells - specialized for antigen capture
Mature cells - T cell stimulation