Immune System

what are the 2 types of immunity

innate and aquired

_________ is the first line of defence against intruders and responds the SAME way to ALL foreign substances

innate immunity

T/F: innate immunity is a more generalized system

true

innate immunity provides protection through skin and ______________, and through ________ cells and __________

muscous membranes; immune; proteins

within innate immunity we have a 1st and second line of defense, what are they

1st: barriers; 2nd: inflammation

examples of physical/mechanical barriers in the first line of defence in innate immunity

skin/hair, mucus membrane, tooth enamel, stratified cell layers

examples of chemical barriers in the first line of defence in innate immunity

mucus, oily skin, ear wax, stomach acid/enzymes

what is the second line of defense for innate immunity

inflammation (made of chemical, vascular, and cellular responses with phagocytes and complement proteins killing foreign invaders)

how do immune cells distunguish between self and “non-self”

through the MHC proteins (major histocompatibility complex proteins)

• all nucleated cells and platelets contain MHC I

• MHC II is on antigen presenting cells (macrophages, B cells, dendritic cells)

T/F: not all immune cells have MHC I

false

natural killer cells do what and how

directly kill targeted cells by recognizing at least 1 of these 3 things

• the cell has no MHC I molecule

• it recognizes MICA (an abnormal form of the MHC I molecule that is missing the beta 2 protein)

• recognizes the IgG antibody

Once it recognizes one of these 3 things, it kills through perforins and granzymes

perforins

create pores inside the membrane

steps of a natural killer cell’s “killing”

1. the natural killer cell binds, recognizes foreign invader → aggression

2. releases perforins and granzymes

3. perforins create pores inside the membrane

how does a natural killer cell let a healthy cell go

natural killer cell binds, recognizes healthy cell, no aggression

if innate immunity fails ______ immunity takes over

acquired (also called adaptive)

acquired immunity is made of what cells

T cells, B cells, and antibodies

aquired immunity targets ______ so we can _______ and attack again

memory; remember

what are the 2 types of acquired immunity

active and passive

active aquired immunity

our immune system creates it’s own defenses/antibodies

passive acquired immunity

reciveing antibodies from another source

T/F: you can naturally acquire or artificially acquire active immunity even tho the idea is that our body makes the antibodies

true, beacuse you can artifiically aquire it through a vaccine since that is us being given weak antigens and then our body is still the thing making the antibodies

example of naturally aquired active immunity

being infected by a pathogen and fighting it off

examples of naturally aquired passive immunity

IgG: placenta, IgA: breast milk

examples of artificially aquired passive immunity

anti-venom, serum tranfer

what are the 2 types of active immunitty

cell mediated immunity and humoral immunity

what types of cells are in charge of cell mediate immunity

T-cells (cytoxic or helper)

what type of cells are in charge of humoral immunity

B cells, plasma cells, antibodies

in cell mediated immunity this is an _______ problem meaning what

internal, meaning the cell has already been invaded by the virus so we need to kill the cell itself

humoral immunity is an ________ problem meaning what

external, meaning we can kill the foreign invader from outside the cell before it invades

cytotoxic T cells do what (very basic definition)

kill viruses and tumor cells

helper T cells do what (very basic definition)

use chemical messengers to activate other cells such as the cytotoxic T cell

basic version of how B cells kill a foreign invader

creating plasma cells and antibodies

boooo a virus has infected a cell, following the cytotoxic T cell pathway of cell mediated immunity, what happens next

virus infected cell presents viral peptide on MHC I (MHC I from infected cell has a self antigen that the viral peptide binds to)

what happens after the viral peptide is presented on MHC I of an infected cell (aka what is step 2 of the cytotoxic T cell pathway of cell mediated immunity)

CD8 (and T-cell receptrs as well) recognize the viral peptide and bind to it

after CD8 binds to the viral peptide, what happens (aka what is step 3 of the cytotoxic T cell pathway of cell mediated immunity)

The T cell makes contact and releases granules (perforins and granzymes). these granules induce self destruction and the virus cannot replicate (viral cell is killed)

boooo bacteria has infected a cell, following the helper T cell pathway of cell mediated immunity, what happens next

MHC II has the antigen of the forign invader, CD4 and T-cell receptor of the helper T cell bind to MHC II

what happens after CD4 and TCR of a helper T cell bind to MHC II of a bacteria (aka what is step 2 of the helper T cell pathway of cell mediated immunity)

the T helper cell secretes cytokines to draw in other immune cells such as cytotoxic T cells (but also cells such as phagocytes and B cells),,, then the cytotoxic T cell goes forward with the killing of the infected cell

MHCs

present on peptides on the cell surface for recognition by T cells

MHC I

presneted on all nucleated cells and recognized by cytotoxic CD8 and T cells

MHC II

presented on antigen presenting cells such as dendritic cells, macrophages, or B cells and is recognized by CD4 and T helper cells

for T cell development where do T cells originate

bone

even tho T cells originate in the bone, there are some chemicals that draw them to what organ (also name the chemicals)

the thymus; thymosin, thymotaxsin, and thymopoetin

after T cells move to the thymus, thymic factors produce RAG1, RAG2, and CD proteins… what do the RAG proteins do

RAG1 and RAG2 produce T cell receptors (TCR) with a specific shape

after T cells move to the thymus, thymic factors produce RAG1, RAG2, and CD proteins… what do the CD proteins do

CD molecules form CD4 and form CD8

each almsot developed T cell now has a small CD4 and CD8, if the CD4 binds first what does it bind to and what does this cause

CD4 would bind to MHC II which would upregulate CD4 and downregulate CD8 creating a T helper cell

each almost developed T cell now has a small CD4 and CD8, if the CD8 binds first what does it bind to and what does this cause

CD8 would bind to MHC I which would upregulate CD8 and downregulate CD4 creating a cytotoxic T cell

after a cytoxic T cell or T helper cell is fully formed, it breaks it’s bond with the other cells MHC and travels where

outside of the thymus to the lymph nodes and spleen ready to fight infections

T helper and cytonoxic T cells can also become what via cytokines

T regulatory cells

there is a bacteria floating around,,, it has antigens as do most bacteria,,, what is the first step of humoral immunity that follows to kill the bascteria cell

antigen binds onto B cell receptor of a naive B lymphocyte, this activates the B lymphocyte

once the B lymphocyte is activated what comes next in the humoral immunity pathway

receptor mediated endocytosis occurs to pull in the antigen and create MHC II

in the humoral immunity pathway, once the naive B cell undergoes receptor mediated endocytosis to take in the antigen and create MHC II what happens

a T helper cell binds to the B cell to produce IL4 and IL5 which are needed for future steps

After the T helper cell binds to the B cell and produces IL-4 and IL-5, what is the next step in humoral immunity

IL-4 stimulates proliferation of the B lymphocyte (it makes copies of itself - also called clonal expansion)

after the B lymphocyte prolfierates, what is the next step in humoral immunity

IL-5 causes differentiation to create either a memory B cell or plasma cells (a memory B cell is just another copy so we can store it for later to eventually be activated into plasma cells, plasma cells are able to secrete antibodies specific to the antigen

what are the 3 functions of antibodies

neutralization, activating complement system, opsonization

antibodies that bind to and inactivate viruses and toxins are called ________ antibodies

neutralizing antibodies

antigen antibody complexes activate the __________ system (also called the _________ pathway), triggering its antibacterial activity

complement; classical (this is the complement protein pathway at the end of inflammation)

opsonization

antibodies that facilitate phagocytosis of foreign substances

antibody structure

there are variable regions and contant regions; variable regions are ones which differ between all antibodies, constant regions are similar across all antibodies (contant region is in the center of the Y, variable region is at the top of the Y)

what happens if T or B cells react to healthy cells

leads to autoimmune diseases (when our T cells and B cells react and kill our healthy cells)

how does out body prevent itself from killing health cells

via central and peripheral tolerance

central tolerance

this is how our body prevents T and B cells from killing healthy cells

basically lymphocytes with receptors specific for self-antigens are deleted in the thymus or bone to avoid producing “self-reactive T cells” but this doesn’t always work so we also have another type of tolerance

peripheral tolerance

if self reacive T cells escape the thymus or bone, peripheral tolerance ensures they are deleted

this is done by T regulatory cells suppressing excessive immune responses and by dendritic cells destroying the self-reactive T cells

if a pathogen or organism gets past the 1st and 2nd lines of defense (barriers and inflammation) then we have 4 different processes that can happen:

1. B lymphocytes recognize the pathogen and begin producing antibodies to neutralize it or label it for destruction (humoral immunity → memory B cell)

2. Helper T-lymphocytes (or B cells) recognize the pathogen as non-self and trigger B cells to divide, become plasma cells, and produce antobodies (humoral immunity → plasma cell)

3. in case of virus, T cells recognize viral cell with MHC and antigen presentation to destory (cytotoxic T cell mediated immunity)

4. Helepr T cells recognize pathogen as non-self and release cytokines, drawing immune cells to destroy infected cell (T helper cell mediated immuntiy)

allergy

hypesensitivity of immune system to typically harmless substances in the environment

allergies can include any of the following

respiratory, food, atopic dermatitis, allergic asthma, drugs

many allergices are ___ mediated meaning it’s responsing to that antibody

IgE

upon first exposure to an allergen what happens (step 1)

B cells activate, proliferate, and differentiate (humoral immunity stuff)

after exposure to an allergen, then the B cell activation, proliferation, and differentiation, what occurs

plasma cells secrete the IgE antibody

after the IgE antibody is secreted in allergy responses what occurs

the IgE antibodies bind to mast cells which degranulate releasing histamine which causes typical allergy symptoms

when an allergen enters the body for a second time, why is this process faster

because the mast cell and IgE antibodies can just bind directly to the antigen since the B cells already have B memory cells now from that humoral immunity process

hypersensitivity reactions can differ slightly from allergies in what way

they have different antibodies associated which cause slightly different physical reactions

type I hypersensitivity reaction

this is your “typical” allergic reaction (seasonal allergies, anaphylaxis, peanut allergies, etc) involving the IgE antibodies

type II hypersensitivity reaction

this involved both IgG and IgM antibodies and is more commonly called autoimmune hemolytic anemia (basically what is sounds like,,, our body is killing our own RBCs)

type III hypersensitivity reaction

this involdes IgG, IgM, and IgA antibodies and can present through RA and lupus

type IV hypersensitivity reaction

this involves T cells and macrophages and presents like contact dermatitis or MS

what medications can help with allergy symptoms (remember they cannot be cured, only symptoms can be managed)

antihistamines, bronchodilators, inhaled corticosteriods, antibiotics, epinephrine injector

short term stress can be beneficial,,, why

it enhances primary immune responses by increasing circularing cytokines (IL6, TNF, etc)

ex: if this level of stress is experienced during vaccinaion, wounding, certain infections, etc, then we can have increase efficacy of vaccine/wound healing and increased resistance to infection

however it can cause some harmful things if this level of stress is experienced during an allergen induced immune reacton leading to increased inflammation and potential autoimmune disease

effects of chronic stress

suppresses immune function by reducing leukocyte mobilization, reducing antibody production, and reducing natural killer cells activity

T/F: exercise can enhance or supress immune function

true

_____________ increase during rest after exercise ends

neutrophils and macrophages

_________ increase immediately and during exercise but decline after long duration

natural killer cells

regular exercise _________ proinflammatory cytokines

increases

T/F; regular exercise delays the decline of immune function that occurs with aging

true

moderate exercise = _________ effect on immune system

positive

high intensity or extreme duration can ________ immune function

supress

HIV tranmission

unprotected sex, multiple sex partners or the presence of other STIs, IV drug use, mother-child transmission

rare: animal bite, transfusions, wound-wound, unsanitary medical practice

not possibe: saliva, tears, sweat, air, skin contact

what is the first step in the HIV life cycle

HIV binds to CD4 on a T helper cell

in the HIV lifecycle what happens after HIV binds to CD4 on a T helper cell

HIV merges with the cell membrane

what happens in the HIV lifecycle after it merges with the CD4 membrane

once inside HIV releases reverse transcriptase to convert it’s RNA into DNA

after HIV convers its RNA into DNA what does it do

it releases integrase which basically means it inserts this new DNA into the cells nucleus to integrate it into the cells DNA

after the HIVs DNA is in the nucelus, what happens

it makes chains of HIV proteins to help build more HIV

after making the long chains of HIV proteins inside the cell what happens

new HIV proteins assemble into immature HIV at the cell surface

once the new immature HIV cell is created at the cell surface thrugh proteins assembling what happens

protease breaks up the long protein chains to create a mature virus, this is then released out of the T helper cell (this also kills the T helper cell in the process)

threshold of CD4 for asymptomatic HIV

500 or more CD4/mm3 still, no symptoms for 1-20 years, clinically healthy and can perform normal activity, may have some fatigue and swollen lymph glands

symptomatic HIV threshold

200-500 CD4 cells/mm3

AIDS threshold

less than 200 CD4 cells/mm3

HIV treatment

cannot cure, but can prolong CD4 cell death process and therefore prolong life and can reduce transmissibility to other people as medicines stop certain phases of the HIV life cycle