BL Immunology Unit 1 Flashcards
innate immune system is necessary to activate what?
the adaptive immune system, T and B cells
how quicky is skin replaced?
every seven days
how quickly are the intestine cells replaced?
every 3 days
what can survive on skin and what is killed?
staphylococci can survive, but ecoli dies within minutes of landing on skin via toxic proteins
what proteins are made by epithelial cells to defend the skin?
defendins or cathelicidin families. Small proteins made by epithelial cells, or brought to them by white blood cells.
cathelicidin are ______ charged?
positive. (cathelicidin=CATatonic HELICal). Bind - charged pathogen membranes. Insert themselves into lethal pores
how many bacteria live on/in us?
10^4 bacteria in gut. 10^10 bacteria on skin.
innate immunity
one of our sense organs. Immune system is designed to detect intruders and arrange for inactivation, destruction, . Recognizes molecular motifs.
what are the 3 things innnate immunity recognizes:
- foreign molecular structures called pathogen-associated molecular patterns (PAMP).
- Stress or damage indicator molecules expressed by body cells, caused by damage associated mollecular patterns (DAMP).
- Absence of certain normal cell surface molecules, which would indicate a prroblem done by NK cells.
most cells have some ________ on surface or inner membrane.
PRR. Pattern recognition receptors. On surface/inner membrane.
what are TLR’s?
Toll like receptors. There are ten of them. Homologous to the toll gene of the fruit fly. Each one can recognize foreign molecular structures.
TLR4 binds what?
liposaccharides (part of cell wall of gram negative bacteria). TLR2 binds peptidoglycan (gram positive bacteria), TLR3 binds double stranded RNA.
what happens when TLR or a WBC passes by an infected wound?
bind the foreign pattern–>signal cascades activated–> expression factors cause/increase inflammation–>factors (cytokines/chemokines) are released
what is the point of inflammation?
inflammation is the increase in blood vessel diamater, stickiness, leakiness.
Increases efflux of fluid and phagocytic WBC into tissue to get defense and healing agents into damaged/invaded area
what is the net effect of TLR cascades?
activate the mother of all inflammatory transcripton factors: NF-kB.
All TLR except TLR3 use the IRaK pathwaywhich does this. Goes into the nucleus, permits transcription of pro-inflammatory genes. Designed to not be a linear cascade so that the body can tolerate things up to a threshold.
what happens when cells get damaged and stressed?
they release a certain amt. of their internal molecules (DAMPs) and then TLRs will bind them to increase local inflammation.
mediator cells such as chemokines are ________ for phagocytic WBCs that flow in from distant areas.
chemotactic
can the innate system adapt to new challnges?
no. it can only see established patterns
what happens if the innate system can’t handle a problem?
it activates the adaptive immune system. This is a slower but stronger and more capable system.
what is the connection between the innate and adaptive immune system responses?
special phagocytic cells interface btw the body and the world (skin, lung, mucosa)–>dendritic cells
what are dendritic cells?
highly branched cells that are the best phagocytes. At wound sites immature DCs get activated by cyto/chemokines and take up what they can. Then they leave and head to the lymph system to show what they ate to lymphocytes. This then is eventually recognized to initiate an immune response
what is recognized in lymph systems by B and T cells when dendritic cells present things?
antigens. (things recognzed by adaptive immunity)
can adaptive immune response develop in the periphery?
no.
what 2 cells divide the work of the immune system up?
lymphocytes and phagocytes
lymphocytes
specialized for recongition of foreignness. Have surface receptors that bind antigenic molecule with the best shape. All receptors on surface are identical.
phagocytes
specialized fore eating/digestion
how many parts of an antigenic molecule fit into a lymphocytes receptors?
10 to 20 amino acids. Called the antigenic determinant or epitope.
what happens to a lymphocyte after an antigen binds?
it is activated, it proliferates (makes clones) by doubling every 6-12 hours. Some cells differentiate and secrete proteins to activate the immune system. Once the clone is big enough and there are enough to fight infection, recovery starts
are lymphocytes short or long lived?
many are long lived. Contributes to immunologic memory. We have memory cells that can active quickly and respond to small amounts of antigen.
what are the 2 kinds of lymphocytes?
T and B. recognize and remove foreign substances.
what do B cells do?
protect extracellular spaces of body (tissue, fluids, secretions). Release antibody into fluids
What do T cells do?
survey the surfaces of body cells (look for ones that ingested antigens, parasites, changed/mutated)
how do T cells recognize antigens?
via surface receptors. When it sees antigens in a DC, it activates, proliferates, and daughters go to invasion site. There they release family of short-range mediators (lymphokines) that call up an augmented inflammitory respone. Moncytes, macrophages attracted.
lymphokines
cytokines made by a lymphocyte
how do B cells work?
arrange for phagocytosis/destruction foreign moecule. Recognize antigens on surface receptors, are activated, proliferate. Then release soluble receptors (antibodies) to do the work.
T lymphocites are also called_________.
T cells
where do T cells develop and mature
develop in bone marrow, mature in thymus
what are the 2 main classes of T cells
helper and killer
Type 1 helper T cells, Th1
recognize antigens and make lymphokine that attracts macrophages to area where antigen has been recongnized. Can wipe out infection/kidney
Th17 helper T cells
similar to Th1, but cause focused inflammation. More powerful than Th1. resist tough infections/organisms. Implicated in autoimmunity
Type 2 helper T cells, Th2
stimulate macrophages to alternatively activate. Wall off pathogens and promote healing after Th1 response. Important parasite immunity
Follicular helper T cells, Tfh
migrate from T cell are to B cell foicles, help activate B cells to make IgM, IgG, IgE, IgA antibodies
regulatory T cells, Treg
make lymphokines that suppres activation and function of T helper cells so they keep immune response in check
Cytotoxic/killer T cells, CTL
detroy body cells they identify as bearing foreign/abnormal antigens
Th1, Th2, Th17, Tfh, Treg all have molecular marker_______
CD4 on surface. Increases antigen affinity, helps activate, tags for identification.
CTL have molecular marker_______
CD8
list steps of T cell mediated immunity:
virus enters body and makes infection–> innate immune response stimulated–>dendritic cells activated–>peptides are loaded into special antigen preserving molecules (MHC Class 2) and recycled to cell surface–> dendritic cell travels to lymphatic node/spleen–>presents to T cells till find one that recognizes–> T cells activated, divide, make 1000’s of daughter cells–>travel through body to find antigen–>inflammation and healing
Cytotoxic T cells are looking for fragments of ________
MHC Class 1. on all cells. Clonse of CTL gene are expanded and daughters circulate through body. When a daughter CTL binds a cell with the same peptide, it signals target cell to commit suicide via apoptosis. Then killer T cell can kill other infected cells.
immunity to antigen means that?
a person has had a previous encounter with it.
B cells
receptors see antigen alone, don’t need to be stimulated by MHC molecule presentation like T cells. Binds antigen, becomes activated to proliferate/differentiate.
what is a fully differented B cell?
plasma cell. Protein production factory that releases soluble versions of its receptors (antibodies)
what do antibodies do?
they bind to the corresponding antigens and neutralize a toxin, preventing from organisms binding target cells
list the 5 classes of antibodies (immunoglobulins):
IgG, IgM, IgD, IgA, IgE. “IG GAMED”
IgG, Immunoglobulin G
most abundant antibody. Two adjacent molecules bind antigen, then cooperate to activate a complement. Only antibody that passes from mother to fetus. 2 light chains, 2 gamma. MW=150,000. appears after IgM after primary immunization. Plasma half life is ~3 weeks. Phagocytic cells have receptors for Fc of bound IgG (opsonizing). 2 IgG’s must be close together to activate first component of complement.
“IgG has the Greatest amount!”
1000 mg/dL of blood
what is complement?
important to disease resistance. Some can burst bacterium via holes in membrane, others attract phagocytotic cells.
IgM
large polymeric immunoglobulin. Better at activating complements than IgG (very good at this). FIRST antibody to appear in blood after a new antigen exposure. only antibody that the fetus makes. Pentamer of basic unit, 2 light and 2 mu chains, extra CHmu4 domain. Linked by s-s bonds and closed by J chain. MW=900,000. unlikely to bind more than 2 of the 10 sites.
“IgM has the Most sites!”
Remember-too much makes blood viscous, so you have to bring in IgG to keep that from happening.
IgD
inserted into B cells membranes as antigen receptor. 2 light, 2 delta chains. Extra long hinge region. MW=180,000. Important as a B cell receptor, so even if found in plasma doesn’t do anything but receptor role.
IgA
most important antibody in secretions (saliva, tears, genitourinary, intestinal fluids, milk). Associated with secretory component (makes it resistant to digestive enzymes). First line of defense against microorganisms trying to get through mucosus membranes. Secreted as a dimer. 2 light and 2 alpha chains. Joined by J chain. So 5 chains total! Wrapped in secretory component. MW=400,000. preferentially made by plasma cells in lymph tissues near mucosal membranes. 2 are made into a dimer by a J chain addition in the plasma cell, then they are secreted into the interstitial space. Secretory component protects it from digestion in the gut
IgE
attach to mast cells. When it encounters antigen, causes them to make prostoglandins, leukotrienes, cytokines and release granules with inducers of inflammation (histamine). Mediators replicate allergy. Resistant to parasites (worms). 2 light and 2 epsillon chains. Extra constant domain. CHepsillon4 and lots of sugars. MW=190,000. Fc end binds to corresponding receptor on mast cells/basophils to trigger them. Cause of hypersenistivity/allergy (or as Dr. Cohen said-it’s your body getting bored and then freaking out about pollen).
“IgE is Extra crazy about Every Allergen!”
antibody is important for extracellular pathogens like_________________ (4 things)
Staph, Strep, Nisseria, Hemophilus. Also impt. In neutralizing toxins (tetauns), blocking spread of virus in blood
where do you encounter the different Ig immunoglobulins?
in the nearby lymph tissues to antigen entrance: T B cells, IgA, IgE. (BATE= Bcell/igA/Tcell/igE)
Draining lymph nodes/spleen: IgM, IgG
where is type 1 immunopathology (immediate hypersensitivity) seen?
in patients who make too much IgE to environmental antigen. Food, allergies, etc.
what is Type 2 immunopathology?
autoimmunity. Due to antibodies that react against yourself.
when can type 3 immunopathology occur?
when someone makes antibody against soluble antigens. If antigena and antibodies are trapped or are too small, they activate compliment and the nearby cells are affected/are casualties.
What is type 4 immunopahtolgy mediated by?
T cells. It can be autoimmune or innocent bystander injury. (forms cavities of lungs in tuberculosis, liver destruction in hepatitis). Damage done by t cells not by bacterium
what is chronic frustrated immune response?
conditions where antigen is not “self” but isn’t something you can get rid of. Eg: your gut bacteria (IBS, celiac), or unless you stop eating it
HIV/Aids basics
infects Th cells since has glycoprotein envelope (gp120) that binds CD4 molecules. Reverse transcriptase used to make DNA inserted into the cell. Activated when this T cell is activated. Progressively lose Th cells.
erythrocytes
red blood cells (5x10^6/uL or 5x10^12/L of blood)
platelets
fragments of megakaryocytes. Used for clotting. 150-400,000/uL
leukocytes
nucleated cells of blood, wbc. Sediment on top of rbc’s when centrifuged to form buffy coat
mononuclear cells
leukocytes whose nucleus has smooth outline includes monocytes, lymphocytes
monocytes
immature, becoming mature macrophages or dendritic cells in the tissue. Sometimes in tissue sections hard to distinguish btw. These two, so they are referred to as mononuclear infiltrate T cells and macro)
polymorphic nuclear cells
cells w/ lobulated nucleus. Aka: granulocytes (have prominent cytoplasmic granules). Contain: eosinophils, basophils, neutrophils)
basophils are closely related to _________
mast cells
how long do neutrophils live?
a few hours in tissue
basophils like _______
basic things. Have histamine. Equivalent of mast cell. Used in inflammation
how many WBC’s exist per unit of blood in an adult?
4500-10500 per uL of blood.
how many neutrophils are there within the WBC content per unit of blood (percent)?
40-60%
how many eosinophils are there within the WBC content per unit of blood (percent)?
1-4%
how many basophils are there within the WBC content per unit of blood (percent)?
.5-1%
how many monocytes are there within the WBC content per unit of blood (percent)?
2-8%
how many lymphocytes are there within the WBC content per unit of blood (percent)?
20-40%
young children have more ________ than neutrophils, so their percentages are reversed.
lymphocytes
what makes up 70% of lymphocytes?
T cells
what makes up 20 % of lymphocytes?
B cells
how many grams of lymphocytes do you have in ~5L of blood?
12g
why do people in developing countries have a higher eosinophil count?
parasites!
what 2 categories is the lymphoid system divided into?
central and peripheral
central lymph organs
where lymphocytes develop: bone marrow, thymus