MHC Class II basics
These immune cells recognize peptide antigens presented by MHC class II molecules.
What are CD4+ T cells?
At six months old, Helen developed pneumonia caused by this pathogen.
This inheritance pattern characterizes MHC class II deficiency.
What is autosomal recessive inheritance?
Name a type of antigen-presenting cells that normally express MHC class II.
What are B cells, dendritic cells, and macrophages?
Helen's CD4 T cell count was much lower than this other T cell population, which remained in the normal range.
What are CD8 T cells?
Helen's low antibody levels can be explained by impaired activation and function of these immune cells.
What are CD4 T cells (helper T cells)?
The 5 HLA class II types.
What are DP, DN, DM, DO, DQ, and DR?
Helen had low levels of these antibody classes.
What are IgG, IgA, and IgM?
Impaired T cell function contributes to low antibody levels for this reason.
What is, because CD4 T cells stimulate B cell differentiation, leading to antibody production and secretion?
Despite her impaired antigen-specific response, Helen responded normally to this nonspecific T-cell mitogen.
What is PHA (phytohemagglutinin)? This helped rule out severe combined immunodeficiency (SCID)
This treatment restored Helen's immune function.
What is a bone marrow transplant (hematopoietic stem cell transplantation)
Defects in these genes cause MHC class II deficiency.
What are the transcription factors CIITA, RFXANK, RFX5, and RFXAP?
What is HLA-DR?
Fluorescent antibody testing also revealed reduced HLA-DQ expression.
Explain why a stem cell transplant might not fully restore CD4 T cells in every MHC class II deficient patient.
What is the continued absence of MHC class II expression on the recipient's thymic epithelial cells? These cells are required for the development of CD4 thymocytes, and aren't replaced by the donor's marrow.