Immunopathology II Flashcards

1
Q

what cell regulates both the humoral and cellular components of the immune system?

A

mature T4 cell

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2
Q

what is the cause of X linked agammaglobinemia?

A

mutation in tyrosine kinase gene responsible for pro/pre B cell signal transduction and continued B cell maturation

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3
Q

which antibody crosses the placenta?

A

IgG

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4
Q

patients with agammaglobinemia are susceptible to what types of infections?

A

enteric viruses and protozoa (no IgA)

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5
Q

what is the main feature of common variable immunodeficiency?

A

hypogammaglobinemia, usually all Ab classes but sometimes isolated to IgG

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6
Q

what is the mechanism of common variable immunodeficiency?

A
  1. intrinsic B cell defect 2. abnormal T cell signaling to B cells (increased suppression or decreased helper activity) 3. inability of B cells to mature into plasma cells
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7
Q

what is the mechanism for selective IgA deficiency?

A

IgA and B cells fail to mature

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8
Q

what are the symptoms of selective IgA deficiency?

A
  1. recurrent GI, respiratory, GU infections secondary to weakened mucosal defenses 2. increased risk for AI disorders (RA, SLE) 3. 40% have anti-IgA antibody
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9
Q

what is the cause of hyper IgM syndrome?

A

failure of T cells to: 1. induce B cell isotype switching from IgM to IgG/A/E, and 2. activate macrophages to remove intracelullar microbes

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10
Q

IgM producing B cells normally activate transcription genes that encode for other Ig isotypes via what signaling process?

A

signaling between CD40 on B cells and CD40L on Th cells

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11
Q

what are the levels of IgM in hyper IgM syndrome?

A

normal or elevated

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12
Q

hyper IgM syndrome has what type of inheritance?

A
  1. X linked 70% 2. autosomal recessive for mutation of CD40 gene or activation induced deaminase enzyme required for switching
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13
Q

what are the clinical symptoms of hyper IgM syndrome?

A
  1. recurrent pyogenic infections (no opsonizing IgG) 2. intracellular infections (P. jiroveci, no phagocytosis) 3. AI lysis (anti-RBC IgM reaction) 4. GIT lymphoid hyperplastic accumulations of IgM+ B cells
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14
Q

what are the features of DiGeorge syndrome?

A

T cell defect, hypocalcemia, cardiac abnormalities, cleft palate

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15
Q

what are the dysmorphologies of DiGeorge syndrome?

A
  1. facial - low set ears, midline clefts, small mandible 2. cardiac - VSD, right subclavian artery derived from pulmonary artery
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16
Q

the x linked pattern of SCID involves what mutation? what is the result?

A
  1. common gamma chain subunit of cytokine receptors 2. impaired lymphocyte development, proliferation, function
17
Q

the autosomal recessive pattern of SCID involves what deficiencies? what are the effects?

A
  1. adenosine deaminase deficiency - metabolites are toxic to lymphocytes 2. failure of MHC II expression - impaired T cell recognition of antigen
18
Q

what are the clinical features of wiskott aldrich syndrome?

A

immunodeficiency, thrombocytopenia, eczema

19
Q

what is the defect associated with WAS? what is the result?

A

WAS protein responsible for cytoskeletal maintenance and linkage of membrane receptors to cytoskeleton - progressive depletion of T and B cells

20
Q

what are the clinical manifestations of WAS?

A
  1. antibody levels normal (IgG) or elevated (IgA/E) with exception of IgM (low) 2. No antibody to polysaccharide antigen, poor antibody response to protein antigen 3. T cell deficit secondary to peripheral, progressive depletion in blood and nodal tissue
21
Q

why is immunodeficiency linked to autoimmunity?

A

persistent infections leads to altered immune response and generation of auto reactive cells

22
Q

what are the mechanisms of T cell loss in HIV infection?

A
  1. viral replication in infected CD4 cells (cytopathic) 2. activation of uninfected CD4 T cells (apoptotic) 3. expression of HIV peptides on infected CD4 T cells (death by CTLs)
23
Q

what are the effects of HIV infection?

A
  1. selective lymphopenia of CD4 T cells with diminished T cell function 2. polyclonal B cell activation with hypergammaglobunemia yet impaired specific B cell response to new antigen 3. altered macrophage function with decreased MHC II expression and antigen presentation
24
Q

what is the pathogenesis of B cell lymphomas following HIV infection?

A

increase in follicular T cells following HIV infection signals germinal centers to proliferate and become hyperplastic

25
Q

what is the histologic appearance of P. jiroveci in the lungs?

A

alveoli filled with foamy exudate, thickened interstitium, coffee bean appearance with silver stain

26
Q

what is the histologic appearance of candida?

A

pseudohyphae and blastoconidia (budding yeast)

27
Q

what is the histologic appearance of pulmonary CMV?

A

enlarged, infected alveolar cells with a single basophilic nuclear inclusion, a perinuclear halo and multiple indistinct basophilic cytoplasmic inclusions

28
Q

what is the main feature of progressive multifocal leukoencephalopathy?

A

reduced amount of myelin - loss of oligodendrocytes

29
Q

what type of tumor is Kaposi’s sarcoma?

A

endothelial type tumor, many RBCs, highly vascular

30
Q

what are the two components of amyloid?

A
  1. amyloid protein fibrils - beta pleated sheets bind congo red 2. pentagonal component - glycoprotein
31
Q

what is the composition of amyloid light chain (AL)?

A

Ig light chains, often gamma, derived from abnormal clones of Ig secreting plasma cells

32
Q

what is the composition of amyloid associated (AA)? when does it occur?

A
  1. related to non-Ig AA protein and its precursor SAA (an acute phase reactant) 2. occurs with inflammatory or infectious states (secondary type)
33
Q

when does the ATTR form of amyloid occur?

A

autosomal dominant deposition of a mutant form of transthyretin in peripheral nerves - leads to polyneuropathy

34
Q

where is AB 2-microglobulin found?

A

deposition in synovium, joints, and tendon sheaths (complication for dialysis)