MHC Class I Deficiency Overview

Individuals that don't express MHC Class I have a deficiency in which cells?

Can individuals that have a CD8 cytotoxic T cell deficiency in expressing MHC Class I express MHC Class I during viral infections?

Does it make sense if a patient has low CD8+ T cell count, but high CD4+ T cell count?

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?

Why would these patients have high serum levels of IgG?

How would it affect the patient if there was a defect in TAP/tapasin?

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.

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.