Lecture 14.2 - SCID Causers

Question 1

What do CD4+ T-cell Defects Cause?

Answer 1

They result in SCID because they are critical to both antibody-mediated and cell-mediated immune response. Remember that B-cell responses require effector T-cell function.

Question 2

Common Gamma Chain Deficiency

Answer 2

The common gamma chain is part of several different cytokine receptors. The receptor chain interacts with Jak3. A deficiency prevents signaling through important cytokine receptors, like IL-2 and IL-7.

Patients have low numbers of T-cells and NK cells, but elevated numbers of B-cells that are dysfunctional.

Question 3

Janus Kinase Deficiency

Answer 3

This prevent signaling through important cytokine receptors, like IL-2 and IL-7.

Patients have low numbers of T-cells and NK cells, but elevated numbers of B-cells that are dysfunctional.

Question 4

CD3 Deficiency

Answer 4

Results in the patient having no CD4+ or CD8+ cells. SCID

Question 5

Complete DiGeorge Syndrome

Answer 5

DiGeorge Syndrome with athymia.

Clinical presentation: patients have a high susceptibility to bacterial, fungal, and viral infections, including opportunistic pathogens.

Treatment for athymia: thymic transplant

Question 6

Zap-70 Deficiency

Answer 6

Zap-70 interacts with ITAMs to help with signal transduction through the T-cell receptor.

Patients have no CD8+ T-cells and normal numbers of non-functional CD4+ T-cells. SCID.

Treatment: bone marrow transplant

Question 7

Omenn Syndrome

Answer 7

Results in low numbers of RAG genes.

Patients do not have B-cells and have very low T-cell numbers that are auto-reactive.

SCID and autoimmune disease.

Treatment: bone marrow transplant

Question 8

Bare Lymphocyte Syndrome

Answer 8

Patients lack expression of MHC Class II molecules and are unable to mount acquired CD4+ T-cell response or acquired B-cell response.

SCID

Question 9

Wiskott-Aldrich Syndrome (WAS)

Answer 9

T cells reorganize their cytoskeleton so that they can deliver their effector molecules directly onto their target cell. A defect causes a cross-talk deficiency that prevents proper cytokine signaling from effector T-cells to B-cells and macrophages.

SCID

Question 10

Adenosine Deaminase or Purine Nucleotide Phosphorylase

Answer 10

These both result in accumulation of toxic nucleotide catabolites that kills all lymphocytes during their development.

No B-cells or T-cells = SCID