September 29, 2015 - B-Cell Defects

Question 1

Humoral Immune Deficiency Presentation

Answer 1

Recurrent sinopulmonary infections such as sinusitis, otitis media (ear infection), and pneumonia.

These often present after 6 months of age when maternal Ab titers wane.

Question 2

Otitis Media

Answer 2

Ear infection.

Question 3

Causes of Humoral Immunodeficiency

Answer 3

1. Abnormal B cell maturation resulting in low (or no) B cell numbers. No B cells, no antibody.
2. A defect in the Ab making ability of the B cells. B cells are present, but they can’t make antibodies.
3. A defect in the ability of B cells to respond to antigen, resulting in abnormal antibody production. B cells can make antibody, but can’t get the signal to do it.

Question 4

Agammaglobulinemia

Answer 4

Abnormal B cell maturation. Absent B cells.

85% due to X-linked agammaglobulinemia (XLA or Bruton agammaglobulinemia).

Question 5

Hypogammaglobulinemia

Answer 5

Low IgG, IgA, or IgM (not none)

Question 6

Clinical Presentation of Agammaglobulinemia

Answer 6

Recurrent sinopulmonary infections

Infection with encapsulated organisms

May present with neutropenia

No lymph tissue

Question 7

Auto-Immune Disease and B-Cell Defects

Answer 7

If B cells are present, but can’t make the proper antibody, the risk for AI diseases goes up.

Most common are autoimmune cytopenias.

Question 8

Common Variable Immune Deficiency (CVID)

Answer 8

Decreased level of at least two Ig isotypes, usually IgG and IgA.

Impaired specific Ab production leads to poor vaccine response.

1/50,000 Caucasians

Question 9

IgA Deficiency

Answer 9

The most common form of deficiency.

Increased susceptibility to sinopulmonary infections, though most are asymptomatic.

Question 10

IgA Deficiency and IVIG

Answer 10

May develop anaphalaxis. Do not administer.

Except in real life where it doesn’t really matter.