Microbiology: Immunology

Antigen

any molecule that can bind to immune system componnts (antibodies, B cell receptors, or T cell receptors)

epitope

three domensional region of an antigen that is recognized by the immune system (i.e. antibody)

-different receptors will recognize each one

immunity

the state of protection from infectious disease

types of immune systems

-innate

-acquired

innate

cell mechanism that will protect the host in a non specific manner

ex: skin and lysozyme

acquired immunity

cells and mechanisms that defenbd the host from infection by other organisms with the ability to recognize and remember specific pathogens in a specific manner

ex: B cells, T cells, antibodies

types of acquired immunity

1. humoral-antibodies

2.cell mediated- T cells

3 major purposes of the immune system

1.identify non-self meaning not normal

2.destroy that which is non-self

3.prepare to 2nd exposure or non-self

**innate immunity does the first two

***acquired does all 3

non-self may include

1.bacterial

2.viral

3.protozoa

4.fungal

5.cancer cells

lines of defense

-innate, nonspecific

-acquired, specific

types of innate, specific

1.first line of defense

2.second line of defense

first line of defense

a surface protection composed of anatomical and physiological barriers that keep microbes from penetrating sterile body compartments

second line of defense

a cellular and chemical system that comes immediately into play if infectious agents make it past the surface defenses

first line of defense examples

1.physical barrier-skin, mucous membanes

2.chemical barriers-secreted like lysozyme

3.genetic compounds

second line of defense examples

1.phagocytosis-LPS like lipid A

2.inflammation-swelling which brings imunne cells to that area

3.fever-denatures proteins-1 degree structure and lose function

acquired, specific types

third line of defense

third line of defense

includes specific host defenses that must be developed uniquely for each microbe through the action of specialized white blood cells

two types of third line defense

1.active-infection-infected and producing memory cells, vaccination

2. passive-maternal antibodies-mather passeds antibodies through breast milk so the child has a little immunity

ex: B cells, T cells and their effects

lymphocytes include

-B cells

-T cells

* type of acquired immunity

B cells

produce antibodies, produced in bone marrow

3 types of B cells

naive B cells, pasma cells, memory B cells

(naive turns into either plasma or memory)

naive B cell

cell that has not seen antigen or germ

plasma cells (effector cells)

have seen the antigen and are now producing antibodies-left bond marrow

memory B cells

wait for secondary infection

T helper

sound the alarm, tells immune system that we have an infection

-has naive, effector, memory `

T cytotoxic

kill using apoptosis

-has naive, effector, memory

phagocytic cells

phagocytosis

just phagocytic

-Eosinophils-for parasites

-Neutrophils-for bacteria (majority of pus are dead neutrophils)

APCs stands for

antigen presenting cells

*look at the antigen and inspect it

3 types of APCs

1.Dendritic cells-inbetween

2. B- cells- type of lymphocyte (acquired)

3.macrophages (inbetween acquired and innate)

how phagocytosis works

antigen is phagocytosed by phagocytic cell-phagositic vesicle fuses with primary lysosome to form a secondary lysosome

how lymphocytes work

antigen detected-B cell recognizes and reproduces- some are plasma and some are memory-plasma secete antibodies and memory stays dormant until second infection

vaccine

you are given antigens-stimulate immune system-produce memory cells- can take over 2 weeks to recognize the first time

neutrophil characteristics

-innate immune response

-kill bacteria

-most abundant in phagocytic cells

-dead puss

eosinophil characteristics

-innate immune response

-parasitic defense

-allergic response

Antigen Presenting Cells-Dendritic cells

-bridge between innate and adaptive immunity

-can recognize non specifically, but can display to the adaptive immune system

APC macrophage characteristics

-innate and adaptive immunity

-engulf but also display to adaptive immunity

APC B cell characteristics

-adaptive immunity

phagocytic response steps

1.chemotixis

2.recognition

3. ingestion

4.killing

5.elimination

chemotaxis

cells movement towards a chemical stimulus

chemotatic factor

chemicals, such as peptides, derived form complement or cytokines, that attract cells

IL-8

stands for interleukan number 8 is an example of a cytokine that is also a chemotatic factor

-for an immune cell

-also has bacteria driven chemicals

cytokines definition

proteins secreted by many types of cells that regulate iimmune cells

functions of cytokines

-chemotixisis

-proliferation-divide

-differnentiation-naive to memory or plama

**all chemotaxic factors are cytokines but not all cytokines are chemotaxic factors

PAMP stands for

pathogen-associated molecular pattern

pamp definitinon

molecules that are unique to microbes that the innate immunity can recognize

-never found in multicelluar organisms

-found on cell membrane of wall

-displayed by microbes taht are and are not pathogenic

examples

lipid A, techoic acids, dsRNA, mannose

effect it has

innate immunity can immediately recognize and combat invaders displaying PAMPs

PAMP receptors

will bind to PAMP that ia complementary chemically and physically

-binding can be all but covalent

PAMP receptor definition

receptor expressed by the innate phagocutic cell (ie neutrophils) that recognize microbe components

-found in immune cells

what receptors might recognize

-sugars (mannose)

-lipids (LPS)

ingestion

plasma membrane of APC engulfs large particle or even entire cell

-PAMP receptor is still on the inside

killing

primary lysosome is generated by the golgi apparatus

-primary lysosome fuses with phagosome which forms secondary sysosome

digestive enzymes and antimicrobials kill bacteria...ex

-H2O2-reactive oxygen species that steals electrons

-lysoszyme- cleaves NAG-NAM units

-proteases-cleaves protein into peptides and a acids`

lysozyme

antibacterial proteisn secreted in sweat and within the lysosome

elimination

undigested materials and cellular debris undergo exobytosis

exocytosis

-secondary lysosome membrane fuses with the phagocytic cell's plams membrane

-everything inside the secondary lysosome is now int eh extracellular matrix