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USMLE Step 1 > UWorld_Immunology > Flashcards

Flashcards in UWorld_Immunology Deck (11)
1

Characteristics of IgA deficiency

  • due to failure of B cells to switch from IgM to IgA production
  • recurrent sinus & GI infections
  • ==> reaction to blood products due to presence of anti-IgA IgG in patient serum

2

Characteristics of NK cells

  • no CD3/4/8 on surface ==> express CD16 or CD56
  • do not require thymus; present in athymic patients
  • contain porphyrins & granzymes ==> apoptosis
  • activated by INF-gamma & IL-12
  • kill cells with decreased or absent MHC I on surface
    • e.g. tumor cells
  • no antigen-recognition/memory 

3

Characteristics of Wiskott-Aldrich syndrome

  • X-linked
  • combined B & T cell disorder
  • immunodeficiency 
  • eczema
  • thrombocytopenia

4

Characteristics of MHC Class I moleculues

  • gene loci: HLA-A/B/C
  • binds to: TCR & CD8 receptors
  • expressed on all nucleated cells (except RBCs)
  • Fxn
    • present endogenously synthesized antigens (e.g. viral)
    • CD 8+ cytotoxic T cells
  • antigen loading
    • antigen loading onto MHC I in RER after delivery via TAP peptide trasnporter
  • mode of transport to cell surface
    • B2 microglubulin

5

Microscopic steps of inflammation

  • margination
  • rolling
  • activation
  • tight adhesion and crawling
  • transmigration

6

Key molecular components of rolling

  • loose binding via sialyated carbohydrate groups
  • @ PMNs = L-selection
  • @ endothelial cells = E-selectin/P-selectin

7

Key molecular components of tight adhesion and crawling

  • CD18 beta 2 integrins (Mac-1 and LFA-1) bind to ICAMs on endothelial cells

8

Key molecular components of transmigration

  • PMNs squeeze between cells and out of vasculature
  • migrate via integrin attachments and adherence to platelet endothelial cell adhesion molecule 1 (PECAM-1)

9

Recurrent false positive RPR w/negative T. palludum immunoassay ==> dx?

  • anti-phospholipid ab in lupus
  • prolonged PTT no corrected by mixing 
    • parodoxical b/c clotting risk = increased

10

Causes of hyper-IgM

  • absence of CD40 on T-lymphs or deficiency of enzyems that modify DNA in isotype switching

11

Characteristics of polymyositis

  • immune-mediated inflammatory myopathy ==> bilateral proximal m. weakness
  • increased MHC I expression w/autoantigen presentation ==> CD8 infiltration and destruction of muscles
  • increased serum CK and anti-Jo-1 antibodies

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