Adaptive and Innate immune system

Innate Immune system qualites

• non specific response

• exposure leads to immediate max response

• cell mediated and humoral components

• no immunological memory

• found in all forms of life

Phagocytes

use phagocytosis to neutralize/kill bacteria

includes neutrophils and macrophages

1st Response to wounds

1. local macrophages w/i tissue release cytokine (chem messengers)

2. cytokines vasodilate local tissue and recruit neutrophils

3. neutrophils marginalize; ie loosely adhere to vessel walls and poke through in response to the chemotaxis

Phagocytosis

cells engulf and digest foreign substances, used by neutrophils and macrophages

Toll like receptors

located on macrophages; recognize PAMPS and secrete cytokines in response

PAMPS

molecular signals associated with diff tpes of pathogens, initiates killing mech but not going to be specific (no memory)

Complement system

composed of plasma proteins that lyse (destroy) foreign cells

includes mac attack and opsonization

Mac Attack

proteins open a large pore in the cell and water rushes in causing lysis and cell death

Opsonization

• C3B component binds the bacteria; anything studded with C3b at risk for MAC attack or engulfing

• receptors for that complement protein are already on the phagocytes

Opsonin

• part of opsonization

• substance made by body that can bind a phagocyte tightly to a pathogen to enhance phagocytosis

Lyse

to break down or destroy the membrane of a cell, causing it to rupture and release its contents

Adaptive immune system qualites

pathogen and antigen specific response, lag time between exposure and max response, cell mediated and hormonal components, exposure leads to immunological memory, found only in jawed vertebrates

Antigen

any molecule that can trigger an adaptive immune response (production of antibodies) to itself or the cell bearing it

Epitope

the subregion of the antigen to which the antibody binds, multiple distinct antibodies can be generated to different epitomes on the same antigen

Antibody

a blood protein produced in response to and counteracting a specific antigen, leading to the killing of the pathogen or host cell marked by that antigen

Primary antibody response

response to 1st antigen exposure, takes a few weeks, moderate concentration of low-medium strength antibodies

Secondary antibody response

response to subsequent antigen exposure, takes a few days, high concentration of high strength antibodies

Why do we vaccinate?

so we can mount a better and faster antibody response and to create herd immunity

Herd community

how quickly disease spread through population whose immune systems have not been educated on pathogen

RO

basic reproductive number; on average how many non immunized people a single sick person will transmit disease to 

Threshold

1-1/RO; population that needs to be immunized in order to stop a pandemic from happening

B cells

• express B cell receptors which are membrane attached forms of antibodies

• Receptors and antibodies bind antigens/microbes carrying them thereby labeling them for destruction by other cells of the innate and acquired immune system

• when activated B cell secretes antibodies

T Cells

• express T cell receptors which remain membrane bound

• receptors can only bind antigens when co presented by the MHC, they discriminated between self and non self

• can recognize antigens only when they are associated with MHC molecules

Helper T cells

direct the adaptive (and part of innate) immune response

Cytotoxic T cells

• kill by direct interaction

• bind MHC class 1 bound with antigen

• wait for helper T signals to proliferate and destroy infected cells

• do this by releasing perforins and granzymes

How mRNA Vaccines Work

1. scientist generated a mRNA sequence that codes for the virus spike protein

2. the RNA sequence, a blueprint for making the spike, is swathed in a lipid coating for delivery

3. once it arrives, cells read the info in the mRNA sequence to produce millions of copies of the spike protein

4. the protein fragments spur the immune system to produce antibodies that can protect when a real virus enters the body

Class 1 MHC

expressed on teh surface of all nucleated cells

Class 2 MHC 

expressed on the surface of antigen presenting cells such as macrophages and activated B and T cells