immuno exam 2

Question 1

what is rheumatoid factor?

Answer 1

Ag against your own IgG

Question 2

what is a titer?

Answer 2

serologic test that indicates the highest dilution (lowest concentration) of patient’s serum that can react to Ag

Question 3

how do you determine if something has a HIGH titer?

Answer 3

if there is an increase of 4 folds or more

Question 4

what can be used to diagnosis a current, acute infection?

Answer 4

if you’re able to detect IgM Ab in the patient’s serum

see IgG = not current infection
IgG + IgM = acute infection
only IgM = current, acute infection

Question 5

what is an agglutination test?

Answer 5

QUANTITATIVE
use particulate ANTIGEN or latex particles –> particles will clump together as the DIVALENT ANTIBODY molecules will CROSS LINK them together giving rise to a positive reaction

Question 6

what does a button mean in a well plate?

Answer 6

button means the absence of agglutination, blood is settling at bottom of well

the results before the button is the highest dilution/lowest concentration

Question 7

what is a “really” high titer?

Answer 7

when the patient’s serum has lots and lots of Abs –> this can cause buttons in the wells because there’s so many Abs that each RBC will get it’s own instead of bivalent crosslinks that cause agglutination

Question 8

explain viral hemagglutination inhibition test

Answer 8

certain viruses can bind to RBCs, causing cross-linking called hemagglutination

put in virus then Ab/serum then RBC to prevent competition between Ab/serum and RBC to bind to virus –> because this can give you a false negative which is agglutination when you do have the Abs to prevent it

by putting the Abs/serum in before the RBCs, it allows the Abs to neutralize the virus if there is any present in the serum and there is no clumping –> this gives you a positive test for having the Abs against the virus

Question 9

what is the precipitation test?

Answer 9

QUANTITATIVE
soluble ANTIGEN precipitates as its molecules are CROSS-LINKED by a specific ANTIGEN

if there is a excess of Ab or Ag then no lattice is forced, but at the ZONE OF EQUIVALENCE (right amt of Ab and AG) then a LATTICE IS FORMED and precipitation is max

in liquids this will be seen as turbidity while in SOLIDS like agar plates it will be seen as a precipitin line between Ab and Ag (zone of equivalence) –> radial immunodiffusion from well

Question 10

what is the difference between single and double diffusion in precipitation tests?

Answer 10

single = Ab mixed with agar and Ag diffuses from well –> used to measure Igs and other serum proteins based on radial immunodiffusion –> at zone of equivalence precipitin line forms and creates circle

double = both Ag and Ab diffuse into agar –> OUCHTERLONY used to determine whether Ags are identical, related, or unrelated
if 2 Ags are identical then they will each form a precipitin line with the AB at the zone of equivalence but the lines will be fused and indistinguishable

if unrelated then they will each form separate precipitin lines that may overlap

if there is a spur then there partial identity –> the Ag that makes the spur has unique epitopes

Question 11

what is immunoelectrophoresis?

Answer 11

serum proteins are separated by electrical current, Abs diffuse from trough in agar, and precipitin arcs form at zones of equivalence

human serum is placed in central well and is electrophoresed, proteins migrate to different regions. antiserum to human serum is placed in trough –> human serum proteins and Ab diffuse into agar –> precipitate arcs will form in agar

Question 12

what is radioimmunoassay?

Answer 12

sensitive and QUANTITATIVE
often used to measure hormones and drugs in serum/plasma

radiolabeled portein is added in excess and allowed to react with anti-protein Ab in the presence of unradiolabeled protein from px serum

unradiolabeled protein and radiolabeled protein will compete to bind to Ab –> if more of px’s Ag binds then there is less binding of radiolabeled tells you that px’s Ag outcompetes it

Question 13

the amount of radioactivity remaining is a function of…

Answer 13

unlabeled hormone concentration

increased radioactivity = decreased unlabeled conc

decreased radioactivity = increased unlabeled conc

Question 14

what is ELISA?

Answer 14

sensitive and QUANTITATIVE
used to measure serum Abs to specific Ags, hormones, and drugs in serum/plasma

MAKES A SANDWICH

wells coated with Ag –> serum is added, px Ab will bind to Ag –> enzyme-linked anti-human Ab is added which will bind to px Ab –> substrate is added which has color (darker = more Ab binding)

Question 15

what is immunofluorescence?

Answer 15

NOT QUANTITATIVE, only DETECTION

direct fluorescent Ab test –> fluorescent dye is attached directly to Ab that is interacting with Ag on surface of cell

indirect –> fluorescent dye is attach to Ab made against human IgG (basically human Ab binds to Ag then anti-human Ab binds to human Ab) –> the secondary Ab can be from a different animal (this has a brighter signal and increased sensitivity)

Question 16

what is complement fixation?

Answer 16

QUANTITATIVE
to look for specific Ab
inactivate complement in px’s serum, add known amts of Ag to test, add known amts of different animal complement, add sensitized RBCs

pos rxn = NO hemolysis, complement was consumed –> known Ag is mixed with px’s serum containing Ab against Ag then complement will be fixed and no complement is left over to cause hemolysis –> complement is activated only if antibodies are present and bound to antigen –> activated, the complement proteins bind to the antigen-antibody complex and carry out part of their immune job (e.g. cell lysis or opsonization). = complement is “fixed” and no longer able to act on anything else

neg rxn = hemolysis, complement was not consumed –> known Ag is mixed with px serum that DOES NOT have Ab against Ag then complement is NOT FIXED, it’s able to cause lysis of RBCs

basically if the px has the Ab against the Ag then there won’t be hemolysis = pos rxn

Question 17

what is the antiglobulin/coombs test?

Answer 17

used for immune-based hemolytic disease
mainly qualitative

direct coombs = detects presence of Ab on surface of erythrocytes –> blood sample from px with immune-mediated hemolytic anemia, Ab are attached to Ag on RBC surface –> px’s washed RBCs are incubated with coombs reagent (anti-human Ab) –> RBCs agglutinate, anti-human Ag form links between RBCs by binding to human Ab (Performed in patients with auto-immune or hemolytic diseases in which Ab are produced that bind to RBCs)

indirect coombs = detects Ab in SERUM that may bind to erythrocytes –> Take the patient’s serum (contains possible antibodies) –> Mix it with test RBCs (with known antigens) –> If antibodies in serum bind the RBCs, they “coat” them –> Add Coombs reagent –> If agglutination occurs = positive result = antibodies are present in serum (for blood donation and transfusions)

Question 18

what is western blot?

Answer 18

QUANTITATIVE
used to detect proteins separated by electrophoresis (to detect anti-HIV antibodies in a patient)

primary Ab reacts with specific protein

viral proteins are separated by gel electrophoresis –> transferred from gel onto membrane –> patient’s serum is added and Abs bind to viral proteins –> enzyme labeled Ab to human IgG is added and enzyme substrate is then added, colored bands appeat at location of viral proteins

Question 19

what is flow cytometry and FACs?

Answer 19

to COUNT the NUMBER of various types of immune cells in a sample of blood, bone marrow, or lymphoid tissue

2 cell types interact with monoclonal Abs labeled with fluorescent dyes –> cells pass one by one thorugh tube –> as cells pass down tube, laser light causes dyes to fluroresce and sensor counts the cells –> depending on detected charge on each cell, fluorescence allows cells to be counted and cahrge allows cell to be defelected into a test tube

flow cytometry of cells isolated from lymph node, showing cells that are CD4 psotive and CD8 positive (the graph with 4 double positive, double negative, CD4+, or CD8+)

basically cells labeled with fluorescently tagged Ab –> optical sensory detect fluorescence –> charing collar puts + and - charge on fluorescing cells –> deflection plates cause separation of cells with different charges

Question 20

what is the structure of blood group O?

Answer 20

H antigen only

Question 21

what is the structure of blood group A?

Answer 21

H antigen with N-acteylagalactosamine added at the end

Question 22

what is the structure of blood group B?

Answer 22

H antigen with galactose at end

Question 23

how are anti-a and anti-b Ab formed?

Answer 23

probably formed against cross-reacting Ag
via T cell independent B cell activation

B cells carrying reactive receptors are deleted during development in people who carry A, B, or both Ags

A = A antigen, anti-B Ab
B = B antigen, anti-A ab
AB = A and B antigen, no Ab
O = no antigen, anti-A and B Ab
Oh (bombay) = no A, B, H Ag, anti-A, B, H Ab

Question 24

what happens when incompatible blood transfusion occurs?

Answer 24

donor’s RBCs interact with recipient’s Ab leading complement activation

anaphylatic shock due to C3a and C5a
hemolysis of donor RBCs due to membrane-attack complex (C5b, 6,7,8,9)
Hb damages kidneys causing acute renal failure
RBC rags activating clotting pathways causing DISSEMINATED INTRAVASCULAR COAGULATION

Question 25

brief reminder of erythroblastosis fetalis

Answer 25

during first pregnancy, Rh- mother does not produce Ab against Rh+ fetus however after exposure, mother will produce Ab which may be dangerous for second pregnancy with Rh+ fetus this IgG Ab will pass from mother to fetus via placenta and bind to fetal RBCs, activate complement, and lyse fetal RBCs --> cause anemia and jaundice in fetus/newborn

Question 26

what is allo immune hemolytic disease of newborn?

Answer 26

infant with ABO blood group alloimmune hemolytic anemia has lots of spherocytes and large polychromoatophilic cells (reticulocytosis) infant with Rh blood group alloimmune hemolytic anemia has lots of spherocytes, reticulocytes, and nucleated red cells --> intense erythroblastosis is MARKER

Question 27

what is prozone?

Answer 27

too much Ab meaning that every RBC gets it's own Ab so there's too many to create cross-links

Question 28

define hypersensitivity

Answer 28

result of overly aggressive immune responses to EXOGENOUS Ag

Question 29

what are the clinical manifestations of the different hypersensitivity reactions?

Answer 29

type I = systemic anaphylaxis, asthma, allergic rhinitis, allergic conjunctivitis (HAY FEVER), food allergies, drug allergies (penicillin), ezcema, bee venom, latex gloves, angioedema type II = hemolytic anemia, neutropenia, thrombocytopenia, ABO transfusion rxns, Rh incompatibility, rheumatic fever (caused by group A strep), Goodpasture's syndrome type III = systemic lupus erythematosus, rheumatoid arthritis, poststreptococcal glomerulonephritis, IgA nephropathy, serum sickness, hypersensitivity pneumonitis type iv = contact dermatitis, poison ivy/oak, TB skin test, drug rash, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis type IV

Question 30

what is the pathogensis of type i?

Answer 30

environmental triggers = pollen, animal dander, food, insect venom, drugs sensitization causes formed of IgE Ab --> Th2 and Tfh CD4+ T cells and class switched B-cells, T-cell cytokines = IL-4 (CS to IgE), IL-5 (eosinophils), IL-21 (B cell diff), IL 4/13 (mucus, smooth muscle, collagen, and M2 macrophage) Ab bind to mast cells, basophils, and eosinophils via FcepsilonRI receps subsequent exposure to allergens results in DEGRANULATION of mast cells, basophils, and eosinophils inflammatory mediators and chemokines are released in short, sensitization by allergen induces production of IgE, IgE will bind to FcepsilonRI recep of mast cells basophils, and eosinophils, allergen cross-link will trigger IgE degranulation

Question 31

what are the type mediators?

Answer 31

released after degranulation, preformed or de novo synthesis, short lived because they're inactivated by enzymatic degradation - HA = PREFORMED, in mast cells and basophils; vasodilation, increased permeability, and SM contraction - platelet activating factor (PAF) = produced by multiple cell types (basophils, mast cells, eosinophils, neutrophils, monocyte, macrophages, and endothelial cells); vasodilation, increased permeability, SM contraction -slow reacting substance of anaphylaxis (SRS-A) = produced UPON EXPOSURE, mix of many leukotrienes formed after degranulation; increased permeability and SM contraction - prostaglandins = formed after degran; vasodilation, increased permeability, and SM contraction - eosinophil chemotactic factor of anaphylaxis (ECF-A) = PREFORMED in mast cells and basophils; attract eosinohils - cytokines = IL-4, IL-5, IL-9, IL-13, IL-21

Question 32

what are the phases of type i?

Answer 32

immediate (5-30 mins) = vasodilation, SM contraction, increased vascular permeability, mainly due to immediate mediators like HA last phase (2-24 hrs) = INFILTRATON by neutrophils, eosinophils, basophils, and monocytes, tissue damage, due to late mediators (leukotrienes) and action of infiltrating cells

Question 33

non-allergic indvs mout an...to the same allergens that...in allergic individuals

Answer 33

non-allergic individuals mount and IgG response to the same allergens that cause an IgE response in allergic individuals

Question 34

mast cells and basophils dont have...

Answer 34

receptors for IgG

Question 35

what is significant about complements in type?

Answer 35

not involved in type I hypersensitivity since IgE does not fix complement because its IgG and IgM

Question 36

what are the roles of eosinophils?

Answer 36

pathogenesis of asthma and other type I response produce histaminase which implicates them in modulation of type I response

Question 37

in anaphylactoid reactions...

Answer 37

mast cells and basophils degranulate WITHOUT IgE involvement

Question 38

what is atopy?

Answer 38

tendency to develop IgE Ab to commonly encountered environmental allergens by natural exposure in which route of entry of allergen is across INTACT mucosal surfaces

Question 39

what is hygiene hypothesis?

Answer 39

people who grew up in environment with lots of parasites and infections tend to not have allergies

Question 40

which is best for quantitation of specific IgE Ab against suspected allergen?

Answer 40

precipitation

Question 41

explain desensitization

Answer 41

acute (temp) = induced by repeated administration of small amts of allergen at 15 mins intervals chronic (permanent) = induced by repeated administration of gradullay increasing amts of allergen over long period of time

Question 42

what occurs in type II hypersensitivity?

Answer 42

cytotoxic hypersensitivity is caused by Ab directed against membrane components of target cells, which activate complement system or mediate ADCC tissue damage is caused by: complement fixation and complement-mediated lysis, ADCC, cytotoxins produced by NK cells attracted by complement, opsonization basically RBC with Ag on cell membrane, IgG binds to Ag and activate complement, membrane attack complex of complement lyses RBC

Question 43

what are the sources of Ag in type II?

Answer 43

mismatched blood transfusion and RH hemolytic disease drugs that bind to surface molecules of RBCs and platelets creating new epitopes Ab directed against infectious agents that cross-react with self Ag aka molecular mimicry

Question 44

what occurs in type III?

Answer 44

inflammatory response incited by Ag-Ab complex deposited in various organs will activate complement (C3a and C5a are released), neutrophils are attracted by C5a, release enzymes that destroy the endothelium and RBCs escape BVs

Question 45

what is the difference between type II and III?

Answer 45

type II is induced by cell-bound Ag type III is induced by soluble Ag

Question 46

what is arthus rxn?

Answer 46

LOCALIZED inflammatory response following intradermal/subcutaneous injection of Ag mediated by high IgG levels hypersensitivity pneumonitis caused by long term inhalation of mold or other allergens

Question 47

what is serum sickness?

Answer 47

SYSTEMIC widespread immune complex deposition due to coexistence of large quantities of Ag and Ab animal serum, mouse monoclonal Ab, penicillin are common examples

Question 48

what occurs in type IV?

Answer 48

takes hours to days responding lymphocytes could be CD4+ ThI cells, which orchestrate response along with macrophages, or both CD4+ ThI and CD8+ cytotoxic T lymphocytes involvement of CD8+ CTLs is associated with significant tissue damage in short, macrophage will ingest Ag, process it, present as an epitope on its surface in association with class II MHC helper T cell is activated and produces gamma interferon which activates macrophages

Question 49

what are the CD4 and macrophage diseases?

Answer 49

Tb, coccidioidomycosis = granuloma, induced by constituents of bacterium or fungus tuberculin or coccidiodin skin test = induration (48 hrs), induced by PPD or coccidiodin

Question 50

what are the CD4 and CD8 diseases?

Answer 50

allergic contact dermatitis = pruritic, vesicular rash, induced by oil of poison oak or poison ivy, otpical drugs, soaps, heavy metals erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis = target lesion (concentric circles rashes), epidermal necrosis and detachment, induced by herpes simplex virus-I, M. pneumoniae, sulfonamides, and penicillin

Question 51

what are the factors that influence tolerance vs sensitization?

Answer 51

early development (more immature which is why children are more likely to develop tolerance) --> tolerance while later stages --> sensitization simple --> tolerance while complex --> sensitization PROINFLAMMATORY signals promote sensitization (which is why you require immunosuppressive drugs during organ transplants) CHRONICITY of exposure promotes tolerance (continuous stim will cause loss of sense to the Ag) potential cross-reactivity due to molecular mimicy

Question 52

explain central tolerance vs peripheral tolerance in the thymus

Answer 52

central tolerance = negative selection (removing self-reactive cells), autoimmune regulator (AIRE) is a gene that expresses proteins from different organs which is why the thymus removes autoreactive cells in the medulla on behalf of the body), AIRE defects = autoimmune polyendocrinopathy peripheral tolerance = absence of CO-STIM (between CD28 and B7) leads to ANERGY and APOPTOTIC cell death --> Tregs (CD4+, CD25++, CTLA-4+ (inhibitory), FOX3P) which all compete for available IL-2, B7, and release IL-10 and TGF beta

Question 54

what are the different methods of suppression by Tregs?

Answer 54

high affinity IL-2 receptor competes for IL-2, depriving the conventional T cell CTLA-4 competes for B7 so there is no co stimulation Treg cytokines (like IL-10 and TGF-beta) suppress T cell activation TREG IS ONLY CD4

Question 55

what are the risk factors for autoimmune diseases?

Answer 55

genetic predisposition --> rheumatoid arthritis - HLA-DR4 hormonal factors --> 90% of autoimmune diseases occur in women, most frequent during pregnancy environmental factors --> exposure to bacteria and viruses, microbiome may have an effect advanced age and declining numbers of Tregs

Question 56

what are the mechanisms for autoimmune diseases?

Answer 56

molecular mimicry (cross reactive Ab that attacks body's own protein that resemble pathogen) alterations of normal proteins release of sequesters Ags (immune privilege = testes leads to aspermatogenesis, CNS leads to encephalitis, and eye leads to endopthalmitis; intracell = DNA, histones, mitochondria) --> basically all these have their own immune system and if they are expose to our immune system then it will form Ag against them epitope spreading = elicitation of immune response against epitopes that are distinct from and non-cross reactive with original epitope failure of tregs

Question 57

what is the function of procainamide?

Answer 57

induces formation of neoAg

Question 58

what are the mechanisms of tumor immunity?

Answer 58

NK cells attack (direct killing and ADCC) CD8 cytotoxic T cells macrophages (MI) Abs (cytotoxic)) CD4 ThI helper cells

Question 59

what is tumor-associated Ag?

Answer 59

neoplastic cells that carry neoAgs

Question 60

what is M1?

Answer 60

classically activated macrophages polarization: activation of TLR by PAMP/DAMP and IFN-gamma function: proinflammatory, fight infections and tumors

Question 61

what is M2?

Answer 61

polarization: IL-4 and IL-13 (M2a), immune complexes and TLR agonists (M2b), and IL-10 and glucocorticoid hormones (M2c) function: anti-inflammatory (Th2), immune response modulation, healing, and tissue remodeling

Question 62

what are tumor's mechanism of immune evasion?

Answer 62

DOWN REG of MHC class I TAA complexes liberation of Treg-activating substances expression of CTL-inhibitors induction of blocking Ab that block recognition or binding inhibitory Fc receptors

Question 63

what is a marker for multiple cancer types?

Answer 63

CEA is elevated in multiple cancers, most commonly colon cancer --> used to monitor therapy, progression, and recurrence

Question 64

what is alpha-fetoprotein for?

Answer 64

infants with birth defects (neural tube defects) adults with cancer or liver disease

Question 65

what are the nonspecific enhancement of immune response in cancer?

Answer 65

- cytokine - BCG (vaccine for TB) - autologous lymphokine-activated killer (LAK) cells activated in vitro using IL-2 - checkpoint blockade using anti-CTLA-4 and anti-PD-LI monoclonal Abs

Question 66

what are the specific enhancement of immune response in cancer?

Answer 66

tumor-infiltrating lymphocytes (TULs) obtained from surgically removed tumors, expanded and activated in vitro and reinfused into patients --> basically put back in large numbers of cells the px made against tumor that you removed surgically chimeric-Ag receptor modified T cells targeting CD19 in B cell leukemia (CAR-T)

Question 67

explain CAR-T Cell therapy

Answer 67

CAR-T cells are px's own cells genetically modified to express CAR which is a chimeric molecule composed of Ab frag that recognizes target (portion of T cell receptor) and signaling molecules CAR T cells will bind to cancer T cells and kill them once you infuse them

Question 68

explain congenital T cell defect

Answer 68

present in early childhood, as early as 6 months of life frequent infections most severe due to defects in cellular, humoral, and macrophage responses (Th1 helps macrophage become fully activated) severe deficiencies are lethal without transplant hematopoietic stem cell transplant is only possible BEFORE onset of severe infections --> once infections starts then there will be proinflammatory environment making transplants more likely to be rejected

Question 69

explain congenital B cell defect

Answer 69

present in first 6 months of life or early childhood low or absent B cells frequent or recurrent BACTERIAL infections and impaired vaccine responses upper and lower respiratory tract infections, esp with encapsulated bacteria may predispose to bacteremia with encapsulated bacteria and some viral infections

Question 70

explain congenital T and B cell defect

Answer 70

present during early childhood often 1st 6 m of life caused by defected in development of all lymphocytes results in SCID MOST SEVERE form of congenital immunodeficiency onset at 3 months of age of recurrent infections absence of lymphocytes or normal numbers of dysfunctional cells, low Ig, absent of tonsils and lymph nodes pneumocytis pneumonia, candidasis, viral infections are common

Question 71

explain the neutrophil respiratory burst pathway

Answer 71

NADP+ gets converted to NADPH using G6PD --> you then add O2 and 2 e- --> get 2 O2- --> make H2O2 which can leave the cell, be converted to H2O using CATALASE or to HOCl to kill pathogens using MYELOPEROXIDASE

Question 72

how do you interpret at DHR test?

Answer 72

normal = all neutrophils are pos after stim carrier CGD = many neutrophils are negative after stim but there's still pos neutrophils X-CGD = absence of positive cells and only negative cells