Immunodeficiency

Question 1

What histopathology and laboratory abnormalities are seen in B cell deficiencies?

Answer 1

• Absent or reduced follicles and germinal centers in lymphoid organs
• Reduced serum Ig levels

Question 2

What histopathology and laboratory abnormalities are seen in T cell deficiencies?

Answer 2

• Reduced T cell zones in lymphoid organs
• Reduced DTH reactions to common antigens
• Defective T cell proliferative responses to mitogens in vitro

Question 3

What are common infectious consequences of B cell deficiencies?

Answer 3

• Pyogenic bacterial infections

- Enteric bacterial and viral infections

Question 4

What are common infectious consequences of T cell deficiencies?

Answer 4

• Viral and other intracellular microbial infections
  
  • Pneumocystis jiroveci
• Virus-associated malignancies
  
  • EBV associated lymphomas

Question 5

Which area of the lymph node is B cell rich?

Answer 5

Germinal Center

Question 6

Which area of the lymph node is T cell rich?

Answer 6

Paracortex

Question 7

What can happen in any type of immunodeficiency?

Answer 7

• Increased susceptibility to newly acquired infections
• Reactivation of latent infections
• Increased incidence of cancers

Question 8

X-linked SCID

Answer 8

• T cells -
• B cells +
• Serum Ig -
• NK cells -
• Mutation in common gamma chain receptor for cytokine
• No T cell maturation
• No Il-7 or Il-15 signals

Question 9

AR SCID (ADA)

Answer 9

• T cells -
• B cells -
• Serum Ig -
• Accumulation of toxic metabolites in lymphs

Question 10

AR SCID (PNP)

Answer 10

• T cells -
• B cells +
• Serum Ig +
• Accumulation of toxic metabolites in lymphs

Question 11

What type of SCID is missing JAK3?

Answer 11

Autosomal recessive

Question 12

What type of SCID is caused by missing common gamma chain?

Answer 12

X-linked

Question 13

Bruton’s agammaglobulinememia X-linked

Answer 13

• Mother is carrier, manifested in male offspring
• Mutation of Bruton tyrosine kinase (BTK)
• Inability of pre-B cells to develop into mature B cells
• Diagnosed 5-6 mo old
• Repeated bacterial infections
• Lacking all Ig
• No CD19 B cells
• T cells +
• Tx gamma globulin injections

Question 14

DiGeorge Syndrome

Answer 14

• T cell defect
• Dysmorphogenesis of the 3rd and 4th pharyngeal pouches
  
  • Thymus and parathyroid
  • Aortic arch, lip and ears
• Neonatal tetany
• Absent thymic shadow
• Decreased T cells
• 22q11.2 deletion

Question 15

Hyper IgM syndrome

Answer 15

• X-linked
• Mutation in CD40L gene
• Lack of class switching
• Susceptibility with intracellular microbe, pneumocystis jiroveci

Question 16

IgA deficiency

Answer 16

• Most common primary deficiency
• No IgA secreting plasma cells
• Asymptomatic -> recurrent sinopulmonary infections and diarrhea

Question 17

Common Variable Immunodeficiency

Answer 17

• Failure in maturation of B cells into plasma cells
• Low serum levels IgG and IgA
• Normal to low IgM
• Major problems are respiratory and GI infections with pyogenic bacteria

Question 18

Wiskott-Aldrich Syndrome

Answer 18

• X-linked
• Triad of problems:
  
  • Lowered platelet count
  • Skin rashes (decreased IgM)
  • Recurrent bacterial infections
• Unable to respond to bacterial polysaccharides

Question 19

Ataxia Telangiectasia

Answer 19

• Multisystem disorder:
  
  • Neurologic: staggering gate
  • Vascular: abnormal dilation
  • Immunologic: both T and B cell
• Low levels of IgA and IgG
• Inability to respond to skin tests
• Reduction in T cells

Question 20

Leukocyte adhesion deficiency

Answer 20

• Defect in adhesion of leukocytes to vascular endothelium
• Defect on leukocyte
  
  • Selectin ligand
  • Beta chain of integrin
• Limits recruitment of cells to sites of inflammation
• Bacterial infections without pus formation

Question 21

Chediak-Higashi Syndrome

Answer 21

• Phagocytes from pts have giant cytoplasmic granules
  
  • Granules dysfunctional
• Do not have ability to kill bacteria

Question 22

Chronic Granulomatous Disease

Answer 22

• Defective production of reactive oxygen intermediates
• Intracellular survival of microbes leads to granuloma formation
• NBT test for measuring respiratory burst

Question 23

Hereditary angiodema

Answer 23

• Deficiency in C1 inhibitor
• Results in excessive C4 and C2 activation
• Leads to localized edema