Cell deficiency and associated diseases

Question 1

B cell

1. X-linked (Bruton’s agammaglobulinemia)
2. Selective IgA

Answer 1

B cell

1. X-linked (Bruton’s agammaglobulinemia)
2. Selective IgA

Specific Deficiency

1. Absence of B cells: very low immunoglobulin levels
2. Very low IgA levels

Molecular Defect

1. Mutant tyrosine kinase
2. Failure of heavy-chain gene switching

Clinical Features

1. Recurrent bacterial infections, especially of respiratory tract, caused by pyogenic bacteria such as pneumococci
2. Recurrent infections especially of the sinuses and lungs, caused by pyogenic bacteria

Question 2

T Cell

1. Thymic aplasia (DiGeorge’s)
2. Chronic mucocutaneous candidiasis

Answer 2

Deficient component and name of disease:

1. Thymic aplasia (DiGeorge’s)
2. Chronic mucocutaneous candidiasis

Specific Deficiency:

1. Absence of T cells
2. Deficient T-cell response to Candida

Molecular Defect:

1. Defective development of pharyngeal pouches (not genetic)
2. Unknown

Clinical Features:

1. Viral, fungal, and protozoal infection; tetany
2. Skin and mucous membrane infections with Candida

Question 3

Combined B and T cell

Severe combined immunodeficiency (SCID)

Answer 3

Combined B and T cell
Severe combined immunodeficiency (SCID)
Deficiency of both B-cell and T-cell function
Either defective I-2 receptor, defective enzymes, absence of class II MHC
Bacterial, viral, fungal, and protozoal infections

Question 4

Complement
1. Hereditary angiodema

2. C3b
3. C6,7,8

Answer 4

1. Deficiency of C1 protease inhibitor
2. Insufficient C3
3. Insufficient C6,7,8
4. Too much C3a, C4a, and C5a generated
5. Unknown
6. Unknown
7. Edema, esp. pharyngeal
8. Pyogenic infections esp. S. aureus
9. Neisseria infections

Question 5

Phagocytes

Chronic granulomatous disease

Answer 5

Phagocytes
Chronic granulomatous disease

Defective bactericidal activity because no oxidative burst
Deficient NADPH oxidase activity

Pyogenic infections, esp. S. aureus and Aspergillus