Cell Mediated Immunity Flashcards
what percent of peripheral blood T cells are CD4+
- 65%
function of T helper lymphocytes
- secrete cytokines
- induces activation of B-lymphocytes and other cells
function of regulatory T cells
- suppress T lymphocyte proliferation toward the end of an immune reaction
- suppress auto reactive T cells that have escaped negative selection
what percent of peripheral blood T cells are CD8?
- 35%
function of CTLs
- release cytolytic substances such as perforin, granzyme, and ligands directly into target cells
- promotes apoptotic cell death
- virally infected cells and tumor cells
memory T cells
- antigen-specific T cells that persist long-term after an infection has resolved
memory T cells upon re-exposure to cognate antigen
- quickly expand to a large number of effector T cells
memory cell types
- CD4 or CD8
stages of t lymphocyte maturation
- stem cell
- Pro-T
- Pre-T
- Double Positive
- Single positive immature
- naive mature
thymocytes that originate from the bone marrow
- lack expression of the T cell receptor
double negative thymocytes
- do not express CD4 or CD8
- up regulate expression of cell surface glycoproteins followed by TCR gene arrangement
where does maturation of T cells occur?
- in the thymus
two processed of thymic education
- MHC restriction
- self tolerance
MHC restriction
- CORTICAL thymic epithelial cells asks developing T-cells if it recognizes the self MHC molecule it is expression
- correct answer is yes
- positive selection
positive selection and affinity
- want low to moderate affinity
cells that connect bind and recognize self-MHC or bind with too low an affinity
- undergo apoptosis
self tolerance
- MEDULLA thymic epithelial cells asks developing T cells if it recognizes self peptides on MHC molecules
- correct answer is no
- negative selection
negative selection and affinity
- thymocytes that bind self peptides with high affinity
- deletes possible auto-reactive T cells
naive T cells
- single positive thymocytes that leave in a resting phenotype
activation of naive T cells
- single positive T cells
- go from lymph node to blood seeking encounters with pathogen
- TCR binds target peptide
- receives signal to become activated cell
MHC class I displays
- fragments of proteins from pathogens inside cell
MHC class II displays
- fragments of proteins from pathogens living outside a cell
