Immunodeficiency

Question 1

Primary immunodeficiency diseases:

Answer 1

Conditions characterized by intrinsic deficits within the immune system and are caused by inherited or de novo genetic defects.

Question 2

Antibody deficiency pattern of infections:

Answer 2

• Bacteria: pneumococcus, H. flu, moraxella, staph aureus, meningococcus, pseudomonas, campylobacter, mycoplasma, ureaplasma.
• Virus: common respiratory especially enteroviruses, rotavirus.
• Protozoa: giardia, cryptosporidium.

Question 3

Combined immunodeficiency pattern of infections:

Answer 3

• Bacteria: listeria, enteric flora.
• Virus: herpesviruses, RSV, influenza, parainfluenza, measles.
• Fungi: pneumocystis, candida, cryptococcus, histoplasma.
• Protozoa: toxoplamsa, cryptosporidium.

Question 4

Cellular immunodeficiency pattern of infections:

Answer 4

• Mycobacteria, especially atypical and including BCG.
• Salmonella.
• Candida.
• Herpes viruses.
• Pneumocystis.

Question 5

Phagocyte defects pattern of infections:

Answer 5

• Bacteria: Catalase positive; mycobacteria including BCG.

- Fungi: candida, aspergillus, paecilomyces.

Question 6

X-linked agammaglobulinemia:

Answer 6

• Susceptibility: pygoenic infections, viral meningo-encephalitis, vaccine strain poliomyelitis, mycoplasma arthritis.
• Features: infancy/childhood with recurrent sinopulmonary pygenic infections, 25% with neutropenia.
• Inheritance: X-linked.
• Diagnosis: Absent B cells, family history, IgG < 100 mg/dl, B cells < 2% of lymphocytes, normal T cell number and function.

Question 7

Common variable immunodeficiency:

Answer 7

• Susceptibility: bacteria, common respiratory and enteroviruses, rotavirus, giardia, cryptosproidium.
• Features: recurrent sinopulmonary infections, bronchiectasis, diarrhea, arthritis, giardia, autoimunity, asthma, lymphoproliferative disease, gastric CA and lymphoma.
• Inheritance: sporadic, autosomal recessive.
• Diagnosis: hypogammaglobulinemia, B cells present. Impaired antibody response.

Question 8

Severe Combined Immunodeficiency (SCID):

Answer 8

• Susceptibility: all infectious organisms including vaccine strains and opportunistic infections.
• Features: failure to thrive, chronic diarrhea, erythroderma or other skin eruption. Specific gene defects may have associated features.
• Inheritance: X-linked or autosomal recessive.
• Diagnosis: lymphopenia in most, diminished or absent T cells in most, poor/absent in vitro mitogen-induced T cell proliferation in all.

Question 9

Treatment of SCID:

Answer 9

Stem cell transplantation.

Question 10

Chronic granulomatous disease:

Answer 10

• Susceptibility: catalase positive organisms, indolent fungal infections.
• Features: recurrent infections. Granulomas of skin, liver, lungs, lymph nodes, viscera, bones, joints. GI/GU obstruction secondary to granulomas.
• Diagnosis: neutrophil oxidative burst assay by flow cytometry using DHR or nitroblue tetrazolium.
• Tx: prophylactic antibiotics, gamma interferon, bone marrow transplantation.

Question 11

Complement component deficiency:

Answer 11

• Susceptibility/Features: recurrent pyogenic infection and also connective tissue disease. Late component deficiency (C5-9) recurrent neisseria species infection., Deficiency of regulatory protein C1 esterase inhibitor is associated with angioedema.
• Diagnosis: CH50 for classical pathway, AH50 for alternative pathway, and/or individual complement levels.
• Tx: prophylactic antibiotics, immunizations with bacterial polysaccharide vaccines.