Questions and Answers
Individuals that don't express MHC Class I have a deficiency in which cells?
CD8 cytotoxic T cells
Can individuals that have a CD8 cytotoxic T cell deficiency in expressing MHC Class I express MHC Class I during viral infections?
True
Does it make sense if a patient has low CD8+ T cell count, but high CD4+ T cell count?
True
Does it make sense that if a patient has low CD8+ T cell count, those T cells are mostly gamma-delta and not alpha-beta?
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Why would these patients have high serum levels of IgG?
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How would it affect the patient if there was a defect in TAP/tapasin?
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Study Notes
MHC Class I Deficiency Overview
- MHC Class I deficiency impacts the expression of CD8+ cytotoxic T cells.
- Individuals lacking MHC Class I show a compromised immune response related to these T cells.
Viral Infections and MHC Expression
- Individuals with CD8+ T cell deficiency can still express MHC Class I during viral infections, but production is limited to a few MHC molecules.
T Cell Count Dynamics
- Low CD8+ T cell counts alongside high CD4+ T cell counts can occur during maturation.
- Double-positive T cells interact with CD4+ and MHC Class II tightly; however, single-positive cells interact weakly with CD8+ and MHC Class I, leading to failed interactions.
T Cell Subtypes in Deficiency
- Patients may exhibit low counts of alpha-beta T cells and predominantly gamma-delta T cells.
- Gamma-delta T cells are unique in that they do not require MHC for recognition, indicating a deficiency of essential alpha-beta T cells.
Immunoglobulin Levels
- Elevated serum IgG levels are common in patients with MHC Class I deficiency.
- The absence of MHC Class I leads to increased antibody production as a compensatory mechanism for reduced cellular immunity.
Impact of TAP/Tapasin Defects
- A defect in TAP (Transporter associated with Antigen Processing) and tapasin affects MHC Class I loading.
- Despite the presence of tapasin, a defect hinders MHC Class I loading, resulting in impaired immune responses.
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Description
This quiz explores the implications of MHC Class I deficiency on immune responses, particularly involving CD8+ cytotoxic T cells. It discusses T cell dynamics, viral infection responses, and the presence of different T cell subtypes in patients with this condition.
