Immuno

Question 1

What are the characteristics of allergic asthma?

Answer 1

only leukotrienes (LTC4, LTD4, LTE4) and acetylcholines have pharmalogic receptor antagonists that offer clear therapeutic benefit

Question 2

What are granulomatous conditions?

Answer 2

• Langhans giant cells are characteristic
• multiple nuclei peripherally organized in the shape of a horseshoe
• the macrophages that form these giant cells are activated by CD4+ TH1 lymphocytes

Question 3

What is a leukemoid reaction?

Answer 3

leukemoid reaction=benign leukocytosis (>50,000/mms)

• in response to undelying condition
  
  • severe infection/hemorrhage
  • malignancy (leukemia)
  • acute hemolysis
• Lab: increased/nml leukocyte alk phos levels
• peripheral smear:
  
  • increased bands
  • early mature neutrophil precursors (myelocytes)
  • granules (Döhle bodies) in neutrophils

Question 4

What is the job of the spleen?

Answer 4

2-fold

1. blood filter=can remove circulating pathogens
2. major site of opsonizing Ab synthesis

• asplenic patients are prone to infections caused by encapsulated organisms:
  
  • S. pneumo
  • H. flu
  • N. meningitides
• spleen=most commonly injured organ with blunt abdo trauma

Question 5

Precursor proteins/peptides responsible for localized amyloidosis

Answer 5

• cardiac atria: atrial natrieuretic peptide (ANP)
• thyroid gland: calcitonin
• pancreatic islets: islet amyloid protein (amylin)
• cerebrum/cerebral blood vessels: beta-amyloid protein
• pituitary gland: prolactin
• immune globulin LC cause multi-organ ayloid deposition in primary systemic amyloidosis

Question 6

Isotype switching

Answer 6

• takes place in the germinal center of the lymph node
• interaction of CD40R on B cells (activated) with CD40L (CD154) on T-cells

Question 7

All of th CDs

Answer 7

• CD4-recognize antigens presented by MHC2
  
  • on the surface of MHC2-restricted T-helper cells
• CD7-multi-chain complex T-cell marker
• CD8-transmembrane protein associated with T-cell receptor
  
  • recognizes antigenic peptide from MHC1
• CD14-surface marker of monocyte-macrophage lineage
• CD19,20,21=mature circulating B lymphocytes

Question 8

HyperIgM Syndrome

Answer 8

• inabiity of B-lymphocytes to undergo isotype switch from IgM to D,G,E,A
• most commonly results in lymphoid hyperplasia and reurrent sinopulmonary infection
• due to genetic absence of CD-40 ligand on T-lymphocytes OR genetic deficiency in the enzymes responsible for DNA modification

Question 9

X-linked agammaglobulinemia

Answer 9

• low/absent circulating CD19,20 pan B cells and pan-hypogammaglobulinemia
• CP: increased susceptibility to pyogenic bacteria, enteroviruses, Giardia lambia (due to the absence of opsonizing and neutralizing Ab)

Question 10

Passage of leukocytes into the inflamed tissue (MR.AT&T)

Answer 10

• Margination
• Rolling
• Activation
• Tight Adhesion and Crawling
• Transmigration

Question 11

Superantigen Activity

Answer 11

• enterotoxins
• oxfoliative toxins
• toxic shock syndrome toxins (TSST-1)
• super Ag interacts with MHC molecules on APC and the variable region of the TLR which causes non-specific, widespread activation of T-cells, resulting in release of IL-2 from T-cells and IL-1 and TNF from macrophages
• TSS is due to the immune cascade

Question 12

Reactive Arthritis

Answer 12

• classic triad:
  
  1. non-gonococcal urethritis
  2. conjunctivitis
  3. arthritis
• HLA-B27 associated arthropathy
  
  • within several weeks after GU or enteric infection
• seronegative spondyloarthropathies
• 20%->sacroiliitis

Question 13

INF alpha and beta

Answer 13

• produced by most human cells in response to viral infections
• suppress viral replication by inhibiting protein synthesis and stimulating apoptosis of infected cells
  
  • limits the ability of viruses to spread through the tissues

Question 14

Achondroplasia

Answer 14

• AD gain of function in FGFR3 (fibroblast GFR3) gene
• indiv: hetero and 50% chance of transmitting to their offspring
• CP: short stature, disproportionately short upper and lower extremities, large head, prominent forehead

Question 15

Chemotactics

Answer 15

• macrophages make IL-8 which induces chemotaxis and phagocytosis in neutrophils
• other chemotactics:
  
  • n-formylated peptides
  • leukotriene B4
  • 5-HETE
  • C5a

Question 16

GvHD

Answer 16

• occurs after allogeneic bone marrow transplantation, transplantation of organs rich in lymphocytes (liver) or transfusion of non-irradiated blood
• pt usually severely immunodef due to primary dz or immunosuppressive meds
  
  • donor T cells from graft survive, migrate into host tissues, recog host MHC Ag ad foreign and become sensitized
  • on activation, donor CD4+ and CD8+ T cell (NOT B-cells) participate in host cell destruction
• skin, liver, GI most freq affected
• early s/s:
  
  • diffuse maculopapular rash-palms and soles, may desquamate
  • GI: diarrhea, intestinal bleeding, abdo pain
  • liver: abnml LFT

Question 17

Pus

Answer 17

• thin, protein-rich fluid=liquid puris, and dead leukocytes, primarily neutrophils
• during infection, macrophages and surrounding endothelial cells release cytokines (IL-8) that trigger neutrophils to enter the site of infection via chemotaxis
  
  • IL-8 also induces phagocytosis in neutrophils once they have arrived
• other significant chemotactic agents:
  
  • n-formylated peptides, leukotriene B4, 5-HETE (leukotriene precursor), complement component C5a

Question 18

SCID

Answer 18

• etiology: gene defect leading to failure of T cell development
  
  • also: B cell dysfxn due to absent T cells
• inheritance: X-linked recessive, AR
• CP:
  
  • recurrent, severe viral, fungal, or opportunistic (Pneumocystis) infxns
  • failure to thrive
  • chronic diarrhea
• tx: stem cell transplant

Question 19

Lymphatic system of extremities

Answer 19

• superficial lymphatic vessels-follow venous sytem
  
  • receive lymph from skin and subq tissues
  • in lower extremities divided into medial and lateral tracks
    
    • lesions on medial foot cause inguinal lymphadenopathy
    • lateral mesions more likely to cause lymphadenopathy in both the popliteal and inguinal areas
• deep lymphatic vessels-follow arterial system
  
  • drain deep muscles and superficial vessels

Question 20

TNF alpha

Answer 20

• TNF alpha inhibitors impair cell-mediated immunity
• all pts beginning tx with TNF alpha inhibitors should be evlauated for latent TB

Question 21

What are the steps of leukocyte transmigration

Answer 21

• margination
  
  • vascular leakage into microvasculature=hemoconcentration and DEC wall shear stress=improved contact of neutrophils with endolthelial lining
• rolling
  
  • neutrophils roll on endothelium via losse binding of (sialylated) carb groups:
    
    • sialyl lew X/PSGL-1 –to– L-selectin on neutophils
    • E-selectin/P-selectin on endothelial cells
• activation
  
  • slow roll=leikocytes sample chemokines=activate integrins via signaling cascade=conformation change in integrins needed for binding
• tight adhesion and crawling
  
  • neutrophils firmly attached to endothelium via CD18 beta 2 integrins (Mac-1 and LFA-1) to intercellular adhesio moecule-1 (ICAM-1)
• transmigration
  
  • PECAM-1, at peripheral intercellular junctions of endothelial cells

Question 22

poison ivy dermatitis

Answer 22

• form of allergic contact dermaitis
• type 4 HSR mediated primarily by T lymphocytes
• CP:
  
  • intensely pruritic erythematous papules, vesicles, or bullae that often form linear patterns
• PP: urushiol [allergenic substance, causes immune resp when attached to proteins (hapten)]

Question 23

what is the major adaptive immune mech that prevents re-infection with the influenza virus

Answer 23

• anti-hemagglutinin Ab
  
  • -humoral resp with Ab directed against Hemagglutinin can neutralize virus and primarily block its binding to the host cells

Question 24

Calcineurin

Answer 24

• essential protein (phosphatase) in the activation of IL-2 which promotes the growth and differentiation of T-cells
• once ativated, dephosphorylates nuclear factor of activated T-cells (NFAT)..allows NFAT to enter ncleus and binf to IL-2 promoter
• immunosuppresants such as cyclosporine and tacrolimus work by inhibiting calcineurin activation

Question 25

Rheumatoid arthritis

Answer 25

• autoimune dz triggered by an unknown Ag
• cartilage components=auto-Ag that activate CD4+ T-cells which in turn stimulate B-cells to secrete rheumatoid factor, an IgM Ab specific for the Fc component of self IgG

Question 26

IgA protease

Answer 26

• produced by:
  
  • N. mening
  • N. gonorrhoeae
  • Strep pneumo
  • H. flu
• cleaves secretory IgA at its hinge region, rendering it ineffective
• secretory IgA exists on mucosal surface and in secretions
  
  • it acts to bind and inhibit the action of pili as well as other cell surface antigens that normally mediate mucosal adeherence and subsequent penetration

Question 27

DILE (drug induced lupus erythematosus)

Answer 27

• abrupt pnset of lupus symptoms
  
  • fever, arthralgias, pleuritis with posittive anti-histone Ab
• linked to drugs metabolized by N-aetylation in the liver:
  
  • procainamide, hydralazine, isoniazid
• genetically predisposed individuals who are slow acetylators are at greater risk for developing DILE