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USMLE Step 1 Immunology

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. Describe the interstitial tissue of a spleen including the sinuses. What type of cells are found in the four structures (cortex - paracortex - medulla and sinuses)?
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
CD56
The interstitial tissue of a lymph node is structured into the cortex on the outside Which is densely cellular which transitions into the paracortex Which is less dense and then the medulla Which is least dense. The cells that inhabit these tissues a
...

2. What is the pathology of acute transplant rejection? is it reversible?
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
It is a localized type III hypersensitivity reaction to an external antigen; localized instead of systemic; ?; intradermal injection of the antigen results in antibody production and antigen antibody complexes deposit in the skin
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic

3. The pathogenesis of contact dermatitis is ________ hypersensitivity
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
type four
Cell mediated due to T cell cytotoxicity reacting to foreign MHCs; few weeks after
Macrophages - Dendritic cells - B cells

4. What is Aldesleukin? What is it used for
Para aortic
Basophils! THey want IG E class switch!
Complement activation (active in both)
A recomb cytokine of IL 2; RCC and metastatic melanoma

5. Name three things that IL 1 does as a cytokine. other than the liver - who secretes IL 1
Induces fever - chemokine secretion to recruit - activates adhesion molecules; macrophages
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
CROSS LINK Beta region on TCR of CD4 cells to the MHC class II on APCs this results in uncoordinated release of Interferon gamma from CD4 Th1 cells and subsequent release of IL1 - IL6 and TNF alpha from Macrophages --> toxic shock syndrome; s. pyogen
A j chain

6. IgG...
opsonizes
In IgE AIHA- it results in MAC attack (remember IgE is not an opsonin!) - in IgG AIHA C3b (and IgG) opsonization results in phagocytosis by fixed macrophages in the spleen
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

7. What are the mediators that mast cells release?
Lymphocytes
Histamine (causes vasodilation) - leukotrienes (causes bronchoconstriction) - chemotaxins for eos - and heparin (increased blood flow needs to be anticoagulated!)
T
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic

8. The idiotype; the Fc portion determines the...
A chemotactic factor for neutrophils
isotype
Chronic granulomatous disease
Macrophages - Dendritic cells - B cells

9. What are superantigens? give two examples.
The igA found in breast milk
CROSS LINK Beta region on TCR of CD4 cells to the MHC class II on APCs this results in uncoordinated release of Interferon gamma from CD4 Th1 cells and subsequent release of IL1 - IL6 and TNF alpha from Macrophages --> toxic shock syndrome; s. pyogen
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Recurrent sinopulmonary bacterial infections after 6 months (d/t mothers igGs transplacental) due to opsonization defect

10. How do you test for type III hypersensitivity?
MHC II - B7
Activates Th1 helper cells; Macrophages
Immunoflourescent staining of tissue biopsies
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage

11. What lymph node drains the lateral side of the dorsum of the foot?
Popliteal
TNF alpha and IL1
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Humoral

12. Describe the capsular structure of a lymph node; What are the functions of the LN?
Capsule of lymph node is made up of type III collagen (made by reticulin fibers!) - extension of this collagen extends into the splenic tissue as trabeculae; nonspecific filtration of lymph by Macrophages - Antibody production (via activation) - stor
Fever - urticaria - arthralgias - proteinuria - lymphadenopathy
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
Pernicious Anemia and Hashimotos

13. What are the two signals required for Th1 cells? what happens after then activated?
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!
Type II hypersensitivity - complement dependent resulting in phagocytosis of RBCs coated with C3b by fixed macrophages in the spleen; Group O mother has anti A - B - IgG Abs that cross placenta and attach to fetal blood group A or B RBCs
pentamer
Paracortex; viral infection

14. What kinds of receptors activate innate immunity?
TLR ad nuclear receptors
IgAs in mothers breast milk!
Macrophages - Dendritic cells - B cells
RNA segment reassortment

15. DTH (delayed type hypersensitivity) is the ________ of a PPD reaction
pathogenesis
IL 4 - 5 - 10 - 6
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)
IL 4

16. What is the main function of IL 12? other than macrophages who else can release IL 12?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Induce differentiation of T cells into Th1 helper cells and activates NK cells also; B cells
Para aortic
A chemotactic factor for neutrophils

17. give an example of how influenza does a major antigenic shift.
RNA segment reassortment
Cytokine release syndrome due to initial release from initial binding (fever etc) and hypersensitivity reaction
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Anti mitochondrial

18. when can graft versus host disease? What is the result?
Interferon gamma and IL 2
Th1; interferon gamma; IL 2 for cytotoxic T cell activation
In any situation where immunologically competent cells are transplanted into immunologically crippled recipient; graft rejects all the cells due to foreign proteins resulting in severe organ dysfunction
Recurrent infections to every type of antigen; bone marrow transplant (be weary of GVH disease!)

19. What is the main function of TNF alpha? How does it do this?
S. aureus - E. Coli - aspergillus
Give a vaccine with a peptide comp from it that the cell mediated immunity otherwise cant get to! like h.influenzae vaccine. then class switching and memory response can occur
IgG
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak

20. What is the end result of complement activation? what bugs are this important for? through what pathway and why?
pentamer
Sinusitis - otitis media - pneumonia
MAC (membrane attack complex) Which is activated by C5b - C9 and results in lysis and cytoxicity by creating pores in the target membrane; encapsulated organisms (S. pnuemonia - H.influenzae - B perfussis for example) and other organisms with non pep
Interferon gamma; Th1

21. What are the function of B cells?
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated
Anti mitochondrial
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
except hyperacute

22. hat is the presentation of Jobs syndrome or Hyper IgE?
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
Anti viral and anti tumor
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal

23. What is the toxicity of azathioprine?
Hemochromatosis
Can be acquired in 20s -30s; increased risk of autoimmune disease - lymphoma - Sp infections; normal number of B cells and no plasma cells and immunoglobulin
Paracortex
...

24. What is the clinical use of Muromonab?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Immunosuppression after kidney transplantation
mesenchymal
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

25. What are the autoantibodies for wegeners granulomatosis?
Influenza; antigenic shift; antigenic drift
C - ANCA (antiproteinase); in neutrophil; c= cytoplasmic
Mycobacterium Tuberculosis - Mycobacterium Avium Intracellulare; Toxoplasmosis Gondii
An antigen encounter (presented by APC for Th2) with Th2 will result in it to go to the cortical section and help with B cell activation; Cytotoxic T cell will enter vasculature/efferent lymph to go kill; B cell will wait for Th2 for activation and t

26. What is anergy? why does this occur?
An anaphylactic immediate reaction; atopy refers to the inherited propensity to develop asthmatic or allergic reactions
C5a
Daclizumab; prevent ACUTE rejection of renal transplant
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance

27. What are the main Cell surface proteins on T cells?
TCR - CD4/8 - CD28 (binds B7) - CD3 (for intracellular transduction) - CD40L
1) VJ light chain random creation 2) VDJ (heavy chain) random creation 3) random combination of light with heavy 4) somatic hypermutation (high frequency mutating that occurs on activation) 5) terminal deoxynucleotidyl transferase (TDT) random additi
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)
Activates Th1 helper cells; Macrophages

28. what prevents NK cells from killing normal cells if their default is to kill?
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
MHC class molecules bind to KIRS or CD94 to prevent killing
IgM and IgA
lowest concentration

29. What lymph node drains the thigh?
Fab portion
False! B cell class switching requires a second signal
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Superficial inguinal

30. what happens in a deficiency of C1 esterase inhibitor? DAF?
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)
Closed circuit where go directly to veins and open where squeeze out of capillary sinusoids and interact with either PALS or with macrophages in the cords of Billroth (for antigen immune function or for blood cleaning or for both) and squeeze back in
Hereditary angioedema; PNH
A recomb cytokine of IL 2; RCC and metastatic melanoma

31. What are the autoantibodies for polymyositis and dermatomyositis?
Anti Jo -1
IgG and IgM bind to pathogens activating C1 convertase and leads to C2 and C4 and then C3 convertase activated
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
When you select for which MHC it will have; take out the lymphs that self react

32. Which helper T cells' development is induced by IL 4? IL 12?
Monoclonal Ab to CD3- blocks cellular transduction and signaling of T cells
Th2; Th1
Superior mesenteric
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

33. IgM can exist as a _______ also
pentamer
Hereditary angioedema; PNH
delayed!
Anti smooth muscle

34. What type of side chains are found on Fc region of an antibody?
Carbohydrate
Increases expression of MHC I and MHC II and also activates NK cells
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

35. To what disease do the autoantibodies to IgG (rheumatoid factor)?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2
Rheumatic arthritis
No because no peptide fragment!

36. Describe the Mannose Lectin pathway
Paracortex
RNA segment reassortment
Some microbial surfaces (only) have mannan binding lectin which activates a protease that cleaves C2 and C4 which combine to make C3. the rest follows the alternative pathway
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear

37. What is the marginal zone of the spleen? what happens there?
Decreased Th1 response; disseminated mycobacterial infections; decreased interferon gamma
Found in the red pulp; contains the cords of billroth or the splenic parenchyma that have APCs/Macrophages that closely interact with the basement membrane of the vasculature and where RBCs squeeze through into the parenchyma and interact with Macrop
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
By transcytosis

38. What is the arthus reaction? What is the difference between arthus and serum sickness? give an example. How do you test for it?
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Brain - eyes - placenta/fetus - testicles; because they can have an antigen in there and not get attacked by immune system because dont have contact with immune system via blood and lymph; if an infection occurs such that trauma results in exposure t
Its main effect is a defect in Ab opsonization for killing
It is a localized type III hypersensitivity reaction to an external antigen; localized instead of systemic; ?; intradermal injection of the antigen results in antibody production and antigen antibody complexes deposit in the skin

39. What can cause a lymph node enlargement?
Mediates septic shock; activates the endothelium for adhesion and dilation and leukocyte recruitment results in vascular leak
Graves
Local infection/inflammation; infection of the ln itself; metastasis
IgE; by activating eosinophils

40. Which disease is associated with DR7?
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Steroid responsive nephrotic syndrome
Paracortex
Delayed type hypersensitivity

41. what cell surface proteins are on all APCs?
Closed circuit where go directly to veins and open where squeeze out of capillary sinusoids and interact with either PALS or with macrophages in the cords of Billroth (for antigen immune function or for blood cleaning or for both) and squeeze back in
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
MHC II - B7
CD21 on B cells (although there is T cell lymphocytosis in EBV)

42. in which immunodef order do you see a lot of pus? no pus?
Binds to Mtor which (like tacrolimus and cyclosporine just in a different pathway) inhibits IL 2 production and thus t cell proliferation in response to IL 2 producton
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
P - ANCA (antimyeloperoxidase); in neutrophil; p= perinuclear
CGD; Jobs syndrome (defect in Neutrophil chemotactic response)

43. T/F B cells do not require a second signal
When you select for which MHC it will have; take out the lymphs that self react
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
False! B cell class switching requires a second signal
Edema and necrosis in that region

44. What is the pathogenesis of IgG AIHA ABO hemolytic disease of a newborn? describe what happens.
A chemotactic factor for neutrophils
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Type II hypersensitivity - complement dependent resulting in phagocytosis of RBCs coated with C3b by fixed macrophages in the spleen; Group O mother has anti A - B - IgG Abs that cross placenta and attach to fetal blood group A or B RBCs
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP

45. What is the pathogenesis of HyperIgE syndrome? What are the labs?
The antibodies (igM or IgG) either neutralize the target directly (cytoxic!) or recruit leukocytes (Neutrophils and Macrophages!) to incite tissue damage
Local infection/inflammation; infection of the ln itself; metastasis
MHC I; from RER with help of the B2 microglobulin
Th cells fail to produce interferon gamma; a lot of IgE

46. What is the pathogenesis of a hypersensitivity reaction?
First a B cell gets sensitized to an allergen - after sensitization - it gets induce by Th2 secreting IL4 to class switch from IgM to IgE - next time blood stream is exposed to allergen these antigens cross like IgEs on mast cells and result in chemi
Antidote for digoxin intoxication
Antidesmoglein
N. meningitidis - H. influenzae - S. pneumonia - Salmonella d/t lack of C3b opsonization for MAC d/t lack of complement activation d/t lack of IgM; MAC is needed by encapsulated avoid by humoral and cell mediated through their capsule

47. Give three examples of bacteria that use antigenic variation and how.
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
Basophils! THey want IG E class switch!
When you select for which MHC it will have; take out the lymphs that self react
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant

48. What lymph node drains the stomach?
Celiac
Coarse Faces - cold (noninflamed d/t inability to attract neutrophils) staph abscesses - retained primary teeth - high igE - dermatologic problems (eczema)
Interferon gamma and IL 2
In IgE AIHA- it results in MAC attack (remember IgE is not an opsonin!) - in IgG AIHA C3b (and IgG) opsonization results in phagocytosis by fixed macrophages in the spleen

49. The MALT/GALT are not...
encapsulated
Basophils! THey want IG E class switch!
The igA found in breast milk
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

50. In order to produce Antibodies - does the antigen have to be phagocytosed? give an example with a bug and an autoimmune (type II hypersensitivity for example).
No! That is why they are different from T cells - they can recognize antigens in free solution; if a bug has a peptide fragment that a mature naive B cell recognizes it will bind to it and cause activation - it then gets activated into a plasma cell!
Adenosine deaminase deficiency (AR) - defective IL 2 receptor (X linked) - and failure to synthesize MHC II; both humoral and cell mediated deficiency
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
Cross link