Micro Revision 3 Flashcards
In a study of immunologic responses to infection, it is observed that infectious agents that gain access to epithelial surfaces elaborate antigens. These antigens are captured by cells, which then carry the antigens to regional lymph nodes, under the influence of tumor necrosis factor (TNF) and interleukin-1 (IL-1). Which of the following types of cells is most likely to carry out this function?
- B cells
- NK cells
- Neutrophils
- T cells
- Dendritic cells
Dendritic cells
are membrane proteins on APCs that display peptide antigens for recognition by T lymphocytes.
Major histocompatibility complex (MHC) molecules ‘’ human leukocyte antigen (HLA) complex’’
The major histocompatibility complex (MHC) is a segment of chromosome
6
Class I and class II MHC molecules are membrane proteins that each contains a peptide binding cleft at
the amino-terminal end
T cell activation requires
recognition of MHC-associated peptide antigen by the TCR
recognition of the MHC molecule by the coreceptor
CD8+ T cells can only respond to peptides displayed by
class I MHC molecules
….. determine which peptides are presented by which MHC molecules
polymorphic residues
Each class I MHC molecule consists of
3 domains of alpha and one beta 2 microgloubin
Each class II MHC molecule consists of
two transmembrane chains, called α and β
The amino-terminal regions of both chains,
called the α1 and β1 domains, contain polymorphic residues and form a cleft that is large
enough to accommodate peptides of
10-30 residues
In class 2 The nonpolymorphic α2 and β2 domains contain the binding site for
CD4 T cell coreceptor.
Class I molecules are expressed on
all nucleated cells
Class II molecules are expressed mainly on
dendritic cells,
macrophages, and B lymphocytes
Class II molecules also are expressed on
thymic epithelial cells
Endothelial cells
other cell types by the INF y
These T cells help the macrophages to destroy ingested microbe
CD4+ T lymphocytes helper cells
