IMMUNODEFICIENCY

Question 1

Host Defense Mechanisms

Answer 1

 Skin and mucosal barriers
 Humoral immunity (B cells, plasma cells, Ab)
 Cell-mediated immunity (T cells)
 Phagocytosis
 Complement

Question 2

Suspecting Immunodeficiency

Answer 2

Look for infections that are:
 Frequent
 Recurrent/chronic
 Unusual organisms
 Organisms that respond poorly to therapy
 Growth retardation
 Family history

Question 3

Humoral (antibody) deficiency associated with:

Answer 3

 Recurrent infections with encapsulated bacteria
 Chronic sinupulmonary infections

Question 4

Cell-mediated deficiency characterized by

Answer 4

 Recurrent infections with
 Viruses
 Fungi
 Opportunistic organisms (PCP)
 Diarrhea, wasting, growth retardation

Answer 5

 Humoral (antibody) deficiency

 Cell-mediated deficiency

 Combined immunodeficiency

Question 6

 Transient hypogammaglobulinemia of infancy

Answer 6

 Slow to develop normal levels of antibody
 Asymptomatic, minor infections
 Low levels of IgG, IgA (IgM usually normal)
 Resolves by 3-6 yo

Question 7

 IgA deficiency

Answer 7

 Most common humoral antibody deficiency
 50-80% asymptomatic
 Recurrent sinopulmonary infections most frequent manifestation
 May have severe malabsorption (chronic diarrhea)
 Isolated low IgA level
 Increased risk of autoimmune disorders

Question 8

Bruton’s X-linked Agammaglobulinemia

Answer 8

No B cells
 Child clinically well for first 6 months of life
 Recurrent upper/lower respiratory tract infections
with encapsulated bacteria (S. pneumo, H.flu)
 Bronchiectasis  chronic cough/increased sputum
 Sepsis, meningitis, skin infections
 Paucity of lymphoid tissue (tonsils, adenoids)
 Markedly decreased IgG, IgA, IgM

O
Treatment: IVIG, antibiotic therapy

Question 9

Common Variable Immunodeficiency

Answer 9

 B lymphs don’t differentiate into plasma cells

 Recurrent sinopulmonary infections

 Low IgG, IgA, IgM

 Treatment: IVIG

 Associated with autoimmune disease,
lymphoma

Question 10

DiGeorge Syndrome

Answer 10

 No T cells secondary to thymic hypoplasia
 “CATCH 22”
 Overwhelming infections with viruses, fungi,
bacteria
 Treatment: correct hypocalcemia, cardiac
defects, fetal thymus transplant

Question 11

SCID

Answer 11

 Defects in stem cell maturation
 Adenosine deaminase deficiency (toxic insult to T
and B cells)
 Manifestations seen in first 3 months of life
 Recurrent, severe bacterial, viral, fungal, and protozoan
infections (usually respiratory infections)
 Failure to thrive, diarrhea, dermatitis, candidiasis
 Most have lymphopenia, decreased IgG, IgA, and
IgM
 Diagnosis made by analysis of T, B, and NK cell subsets
 Treatment: isolation, treat underlying infections,
bone marrow transplant

Question 12

Wiskott-Aldrich Syndrome

Answer 12

 X-linked recessive
 Symptoms in infancy
 Recurrent, severe infections
 Eczema
 Thrombocytopenia (petechiae)
 Low levels of IgM
 Increased risk for hematologic malignancy
 Treatment: manage bleeding/infections, BMT

Question 13

Ataxia Telangiectasia

Answer 13

 Autosomal recessive deficiency in DNA
repair affecting T and B cells
 Progressive ataxia, telangiectasia, variable
immunodeficiency (recurrent sinopulmonary
infections common)
 Increased risk of malignancy (leukemia,
lymphoma

Question 14

Hyper IgE (Job) syndrome

Answer 14

Autosomal recessive
 Symptoms/signs
 Coarse facial features/skeletal abnormalities
 Recurrent staph infections
 Impetigo (resistant)
 Pneumonia with pneumatocele formation
 3 E’s: Elevated IgE, Eosinophilia, Eczema

Question 15

Hyper IgM Syndrome

Answer 15

 T cell abnormality preventing IgM  IgG
 X-linked recessive (males 6 mo-1 year)
 Frequent sinopulmonary infections, diarrhea,
opportunistic infections (PCP)
 Low levels of IgG/IgA, high levels of IgM
 Treatment: Ig replacement

Question 16

HIV

Answer 16

 Retrovirus infecting CD4 + cells
 Vertical transmission, breastmilk, sex
 Wide range of clinical manifestations
 Failure to thrive, fevers, night sweats, malaise,
recurrent thrush, recurrent bacterial infections
 Decreased CD4 count, may have elevated Ig
 AZT x 6 weeks, PCP prophylaxis

Question 17

Chronic Granulamatous Disease (CGD)

Answer 17

 Defective NADPH oxidase
 75% X-linked recessive, 25% autosomal recessive
 Severe, recurrent staph aureus infections of lymph
nodes, and skin (granulomas, heal slowly),
pneumonitis, osteo, hepatosplenomegaly
 Dx: Nitroblue tetrazolium (NBT) test
 Treatment: antimicrobial prophylaxis, IFN-gamma,
BMT

Question 18

Leukocyte adhesion deficiency (LAD)

Answer 18

 Deficient chemotaxis
 Recurrent soft tissue, skin, respiratory
infections, impaired wound healing (typically
no pus, minimal inflammation)
 Delayed umbilical separation
 Increased WBC count
 Treatment: BMT

Question 19

Complement System Disorders

Answer 19

 Defects of early components (C1-C4) associated
with infections with encapsulated bacteria
 Present similarly to humoral immune deficiencies
 Defects of late components (C5-C9) associated with
Neisseria infections
 Also associated with autoimmune-like conditions
 CH50 functional assay assesses entire complement
cascade
 Also may use individual components
 Treatment: treat infectious and autoimmune
sequela

Question 21

 B lymphs don’t differentiate into plasma cells

Answer 21

Common variable immunodeficiency

Question 22

No T cells secondary to thymic hypoplasia

Answer 22

Digeorge syndrome

Question 23

Adenosine deaminase deficiency (toxic insult to T
and B cells)

Answer 23

SCID

Question 24

 X-linked recessive
 Symptoms in infancy
◼ Recurrent, severe infections
◼ Eczema
◼ Thrombocytopenia (petechiae)

Answer 24

Wiskott-Aldrich Syndrome