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USMLE Step 1 Immunology

Subjects : health-sciences, usmle-step-1

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Answer 50 questions in 15 minutes.
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1. What is a factor that is a predictor for a bad transplantation?
They directly stimulate Macrophages by binding CD14; also the alternative complement pathway binds to these host surfaces and induces MAC complex; also TLRs exist for endotoxins; also IgM though not an opsonin can act as a pentamer and trap the antig
Patient has had previous exposure to blood products which result in presence of preformed anti HLA cytotoxic Abs
Th2; Th1
Hemochromatosis

2. What is the autoantibody for SLE that is nonspecific? Specific?
Its involved in inflammation and results in anaphylaxis and neutrophil chemotaxis.
Barrel hoop basement membrane fenestrations
Anti nuclear Antibodies (ANA); Anti dsDNA - anti Smith
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E

3. What can cause a lymph node enlargement?
RNA segment reassortment
Local infection/inflammation; infection of the ln itself; metastasis
Negative!
IL 5

4. Name the three opsonins
Glycoproteins; HLA
CRP - C3b - IgM
Lack of response from lymphocytes when activated; because they are self reactive - this is a form of tolerance
Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate; yes! with immunosuppressants

5. Which cytokines do Th2 release and For what?
Not thymus - BM
Immune complex - Arthus reaction and Serum sickness; they are all a result of antibody- antigen complex deposition resulting in complement activation
IL 4 -5 -6 for B cell class switching - IL 10 to inhibit TH1
encapsulated

6. What are four results of a splenectomy?
...
Anti topoisomerase
CD56
1) susceptibility to encapsulated organisms 2) Howell Jolly Bodies 3) Target cells 4) Thrombocytosis

7. What are the main symptoms of B cell immunodeficiencies?
SP infections
Defect in CD40L results in inability to class switch; a lot of IgM and no IgG - A - E
Its a serine protease that activates apoptosis; NK and CD8
IL 1 and IL 6

8. The pathogenesis of contact dermatitis is ________ hypersensitivity
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
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
Superficial inguinal
type four

9. other than mediating shock - what else does TNF alpha do? who releases it mainly?
Activates Th1 helper cells; Macrophages
MS - hay fever - SLE - goodpastures
T cell activation; no with CD 4 or CD 8
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA

10. What are the main symptoms of T cell immunodeficiencies?
Leukocyte adhesion defect; ataxia telangietasia; ataxia telangiectasia; chediak higashi syndrome; IgA def; Digeorge syndrome; Jobs; Chediak Higashi
Severe recurrent pyogenic sinus and resp tract And increased susceptibility to type III hypersensitivity like SLE
except hyperacute
Intracellular pathogens (acute and chronic viruses and virally induced cancers)

11. From where do cytokines come from?
isotype
Opsonize bacteria (for enhanced phagocytosis) - neutralize viruses (igG) - activate complement (igM and igG) - sensitize mast cells (igE)
Pernicious Anemia and Hashimotos
Lymphocytes

12. What type of cells do NK cells attack? with What tools? by necrosis or apoptosis?
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
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Adaptive uses classic pathway to kill; innate uses alternative pathway to kill
The place of T cell diff and maturation; ant mediastinum above heart; yes; 2

13. What is recomb gamma interferon used for?
Antihistone
Chronic granulomatous disease
acute phase reactants
Digeorge syndrome - 22q11 deletion resulting in failure to develop 3rd and 4th pharyngeal pouches; cardiac and great vessel congenital defects - tetany from hypocalcemia - recurrent viral/fungal infections from T cell deficiency; hypoPTH - hypoCa - a

14. is IgM an opsonizer?
Th cells fail to produce interferon gamma; a lot of IgE
Negative!
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
T cell activation; no with CD 4 or CD 8

15. What does granzyme do? who secretes it?
B - T - and NK cells
Fc
Surrounds the red pulp and begins with PALS and then turns into follicles with B cells/follicles
Its a serine protease that activates apoptosis; NK and CD8

16. What are some catalase positive organisms?
S. aureus - E. Coli - aspergillus
Acts as second signal on B cells to induce class switching to IgE and IgG
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening
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

17. Give three examples of bacteria that use antigenic variation and how.
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
mesenchymal
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
MHC II/CD4 and B7 (on APC) and CD28 (on Th cell); releases cytokines to kill those extracellular buggers!

18. What cytokines do macrophages release? who else can secrete IL 6? IL 12?
IL 1 - IL 6 - IL 12 - TNF alpha; IL 6- Th2 cells; IL 12- B cells
Fc
Popliteal
Lack of MHC class I constant region which it binds or a nonspecific activation signal (TLR)

19. give an example of a virus that uses antigenic variation. What does a major variation result in? minor?
Negative!
Wiskott Aldrich syndrome
Influenza; antigenic shift; antigenic drift
Macrophages - Dendritic cells - B cells

20. IgM can fix complement but...
isotype
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
cannot cross placenta
IgG

21. what characterizes an arthus reaction?
Defect in BTK a tyrosine kinase gene; failed maturation of B cells; X linked recessive
Maculopapular rash (palm - soles - back - neck) - jaundice with bile duct necrosis - hepatosplenomegaly - diarrhea; bone marrow and liver transplants (rich with lymphocytes); SCID patient receiving whole blood transfusion
Edema and necrosis in that region
Defect in B cell maturation; idiopathic - presents at older age and normal number of B cells and hyperplastic germinal centers because B cells can be activated but can not produce Abs

22. What are C1 - C2 - C3 - C4 important for?
Activate B cells - activate Macrophages - kill viruses directly - delayed cell mediated hypersensitivity - acute and chronic rejection
Viral neutralization of igM and IgG!
Axillary
Active; passive - fast but short half life (3 weeks!)

23. are Th cells involved in trapping of antigens of endotoxin/LPS?
Paracortex; viral infection
acute phase reactants
No because no peptide fragment!
Popliteal

24. What is recomb alpha interferon used for?
Internal iliac
Receiving preformed Antibodies
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata

25. What does interferon gamma do? What two type of cells does it attack mostly?
Activates Macrophages and Th1 cells; suppresses Th2 cells; antiviral and antitumor
HBV - HBC - Kaposis - leukemias - malignant melanoma - hairy cell leukemia and condyluma accuminata
Anti IF
IL 5

26. What are the autoantibodies for polymyositis and dermatomyositis?
Anti Jo -1
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
Wiskott Aldrich syndrome
Edema and necrosis in that region

27. What lymph node drains the breast?
IgG
Pernicious Anemia and Hashimotos
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
Axillary

28. Describe the Mannose Lectin pathway
T
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
Increases expression of MHC I and MHC II and also activates NK cells
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

29. What are the sinusoids of the spleen? What is the difference between a spleen and a lymph node?
TGF beta and IL 10
The red pulp of the spleen its where the vasculature channels go through and interact with the parenchyma of the spleen (has macrophages) which empty in the sinuses; they are both encapsulated (with trabeculae) secondary lymphoid organs that trap ant
opsonizes
Lack of NADPH oxidase results in a lack of respiratory burst in neutrophils; susceptibility to catalase positive organisms (S. aureus - E. Coli - Aspergillus)

30. What is the cause of thymic aplasia? What is its presentation? What are the labs?
Intracellular pathogens (acute and chronic viruses and virally induced cancers)
IL 1 and IL 6
Its a serine protease that activates apoptosis; NK and CD8
Digeorge syndrome - 22q11 deletion resulting in failure to develop 3rd and 4th pharyngeal pouches; cardiac and great vessel congenital defects - tetany from hypocalcemia - recurrent viral/fungal infections from T cell deficiency; hypoPTH - hypoCa - a

31. In general What are T cells good for?
Anti viral and anti tumor
Cyclosporine and tacrolimus; sirolimus (as well as hyperlipidemia)
MHC class molecules bind to KIRS or CD94 to prevent killing
Edema and necrosis in that region

32. ________ regulate the cell mediated response.
IL 1 and IL 6
Tumor cells and virally infected cells; perforin pore to secrete granzymes through it; apoptosis
Humoral
Recomb cytokine of GCSF (granulocyte macrophage colony stimulating factor; for recovery of bone marrow

33. What are the function of B cells?
Both decrease cd8 tcell prolif but one through mtor and the other through calcineurin (resp)
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
MHC I - CD16 - CD56
Make antibody - allergy type 1 (igE) - Cytotoxic and immunecomplex hypersensitivity type II and III (igG); hyperacute organ rejection is Ab mediated

34. How do we use thymus dependent antigens to prevent infection from organisms that lack a peptide component?
When you select for which MHC it will have; take out the lymphs that self react
Antiviral for uninfected cells (for future protection) and kills virally infected cells (NK activation)
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

35. What happens in a secondary follicle?
pale central germinal centers
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
MHC class molecules bind to KIRS or CD94 to prevent killing
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation

36. The idiotype; the Fc portion determines the...
MHC II - B7 - CD40 and CD14; CD40 and D14 for FcG and C3b resp
Yes
MS
isotype

37. what mediates the type II hypersensitivity? What are the two different methods?
Lymphocytes
Cyclosporine - OKT3
Antibody mediated cytotoxicity; either complement dependent or complement independent
Anti alpha subunit 3 of collagen on type IV bm

38. which cytokine inhibits TH2 cells? secreted by who?
A recomb cytokine of IL 2; RCC and metastatic melanoma
Scratch test - histamine mediated wheal; radioimmunosorbent assay (detects specific IgEs in serum)
Interferon gamma; Th1
NK cells

39. What is the main cytokine that activates eosinophils?
type four
IL 5
Nuclear remnants that are usually taken out of RBC before complete maturation by Macrophages
Para aortic

40. What is colostrum?
Remove encapsulated bacateria
IgA; sinus and lung infections from lack of secretory defense - milk allergies and diarrhea from giardiasis; Anaphylasix on exposure to blood products with igA
An alpha and beta chain; only on APCs; TCR and CD4; extracellular (phagocytosed by APCs)
The igA found in breast milk

41. How do you test for type III hypersensitivity?
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
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
Immunoflourescent staining of tissue biopsies
They directly stimulate Macrophages by binding CD14; also the alternative complement pathway binds to these host surfaces and induces MAC complex; also TLRs exist for endotoxins; also IgM though not an opsonin can act as a pentamer and trap the antig

42. What are the labs in brutons agammaglobulinemia?
dimer
Rheumatic arthritis
Normal pro B (CD 19 +) - no mature B cells results in decreased total B cell level - and decreased amount of immunoglobulins in each class
Since cant cross placenta most likely means that child was forced early to produce due to an infection (most likely CMV)

43. What is an example of a parasite showing antigenic variation?
Hyperacute; presence of preformed antibodies in the recipient ( to blood groups or HLA )
Trypanosomes with programmed rearrangement (results in recurring fever -- sleeping sickness!)
C3b; coating of a pathogen with molecules that promotes phagocytosis; IgG and CRP
Liver! (they are proteins circulating in the blood)

44. What is the clinical use of Muromonab?
Fab portion
Immunosuppression after kidney transplantation
Proteins; IgG - IgM - endotoxin (microbial surfaces in general - nonspecific ones also) - mannose binding Lectin; classic - alternative - MB pathway (resp)
IgAs in mothers breast milk!

45. what cell surface marker is used for NK cells as it is unique to them?
CD56
IgAs in mothers breast milk!
Periarteriolar lymphatic sheath in the white pulp that surround that dead end of the capillaries in the red pulp - contain T cells
Suppresses immune response (also specifically Th1 cells) and activates Th2; regulatory T cells

46. What is ataxia telangectasia? What is it caused by? What is the triad of presentation? and its labs?
Wiskott Aldrich syndrome
Isotype switching (activated by Th2 cell signals and cytokines) - somatic hypermutation
A B and T cell disorder; defect in DNA repair enzymes; ataxia - telangactasia and IgA def; igA def. and increased AFP
Fibrosis of blood vessels and graft tissue from ischemia; obliterative vascular fibrosis with intimal thickening

47. What lymph node drains the upper limb?
Local infection/inflammation; infection of the ln itself; metastasis
Activates Th1 helper cells; Macrophages
Anti TSh receptor
Axillary

48. What is the pathogenesis of a candida skin test?
Delayed type hypersensitivity
Salmonella - 2 flagellar variants; Borrelia (relapsing fever); and Neisseria gonorrhoaea - pilus protein
From self; from identical twin or clone; from nonidentical individual of same species; from different species; fetus; pig valve
not Ab mediated

49. 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)?
C5a
Septicemia with neisseria; because at least you have C3 to act like a neutrophilic chemotactic and an acute phase reactant
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
Influenza; antigenic shift; antigenic drift

50. What are the two signals required for B cell class switching? Which is the second signal?
S. aureus - E. Coli - aspergillus
CD40 (on b cell) CD40 ligand on Th2 cell; and interleukins (4 -5 -6) from Th2 cell; CD40 is actually the second signal
IgAs in mothers breast milk!
neutrophilia!

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