Linking Apative + Innate Flashcards
What does the cell to cell interaction between T cell and APC (antigen presenting cell) ensure
Correct T cell is activated
What are types of APC (antigen presenting cell)
-dendritic cells (DC)
-macrophages
-B cells
What is the difference between class 1 MHC and class 2
Class 1 - present intra-cellular Ag on all nucleuated cells
Class 2 - present extra-cellular Ag only on professional APC
What is MHC
Major histocompatibility complex
What is the MHC complex complied of
-T cell receptor - contact residue peptide
-peptide in between T cell receptor and MHC
How are MHC genes expressed
Có dominantly expressed = alleles inherited from both parents expressed equally
What is MHC haplotype
Set of MHC alleles present on each chromosome
What does tissue typing require in regards to MHC
MHC molecules (haplotypes) need to match to high degree between host and donor
features of the extra-cellular Ag (antigen)
-presented by MHC class II
-T helper (Th) cells + regulatory T (Treg) cells
-only see Ag presented in MHC class II - express on CD4 surface
-coordinate immune responses
Features of the intra-cellular Ag
-presented by MHC class I
-cytotoxic T + cell/lymphocytes (CTL)
-only see Ag presented on MHC class I - express CD8 on surface
-killed cells infected with intracellular pathogens
What is the role of CD4
Stabilises TCR interactions with MHC class II
What is the role of CD8
Stabilises TCR interactions with MHC class I
Features of DCs (dendritic cells)
-present in all barrier tissues
-immune sentinels
-express PRRs
-do not kill
What are the roles of DCs (dendritic cells)
-scan for infection (via PRRs)
-sample environmental antigens
-take Ag to lymph nodes to talk with T cells
What is the first signal required for T cells to activate
Signal 1 tells the T cell that it recognises the Ag presented by the DC
What is the second signal required for T cells to activate
(Co-stimulation Danger)
-danger signals (PAMPs) up-regulate B7 (CD80/86) on APC
-B7 signals to the T cell via CD28
Features of the T-dependant Ab response
-full effector functions
-can switch isotype
-affinity maturation - can increase its affinity for Ag
Features of T-independent Ab response
-limited effector functions
-no isotype switching
-no affinity maturation
-stimulated by repeating epitopes
-against carbohydrates or non-proteins
How does the B cell work as APC
-B cell presents Ag it recognises to the Th cell
-if Th cell recognises it - means Ag is from a pathogen
-cell gives permission to B cell to respond to
How does immune memory relate to activation of T and B cells
-memory T and B cells easier to activate
-memory T cells activated by more APC types (not just DC)
-memory T cell patrol tissue - focusing on location of last infection = dont need to activate LN
