Lecture 7: T Cells in infection Flashcards
What are the similarities and differences between the 2 Tcells and how they recognise antigens
Both have TCR which recognise antigen presented by MHC and both have CD3 marker.
However
Cytotoxic t cells also have CD8 marker which interacts with class 1 HLA on infected cell whereas Helper t cells have CD4 marker which interacts with class 2 HLA on antigen presenting cell
What is HLA
This is the human genes of Major histocompatibility complex structure on the surface of cells which presents antigens to T cells. they have both class 1 and 2 loci
Compare similarities and differences of the Class 1 and 2 HLA in their where their surface structures are found, gene, and who they present to
Similarities: both polymorphic genes (many alleles) and are co dominantly expressed for each type (mum +dad versions per HLA)
Differences: Class 1 is found on virtually all nucleated cells, whereas Class 2 is found on specialised AntigenPC and B cells.
Class 1 presents to Cytotoxic T cells whereas Class 2 presents to helper cells
Compare the two ways that antigens are usually processed and presented to T lymphocytes by cells using Class 1 or Class 2 MHC
Those with class 1 display a sample of peptides from what the cell is making and metabolising (eg. virus proteins from infected cell)
Whereas class 2 display antigenic peptides of what was phagocytosed by the antigen presenting cell
Describe the process of T lymphocyte activation
- The T cell with the specific binding site that can bind to the presented antigen will become activated
- The t cell then expresses receptors for growth hormone
- After receiving second activation signal of cytokine from helper/inducer cell the lymphocyte is fully activated
- There is proliferation and differentiation into effector and memory cell
Compare the effector for CD8 and CD4 T cells
CD8 T cells effectors have the same specific antigen receptor and look for other cells presenting this antigen to kill them
CD4 effectors are regulators that respond to the same antigen by releasing cytokines
What are typical antigen presenting cells
Macrophages, monocytes, dendritic cells
What are cytokines and what are their purpose
They are low mol weight glycoproteins which regulate the
quality, duration and amplitude of immune and inflammatory response.
Effect is variable depending on concentration, other cytokines present, type of cell recieving and its history
Who secretes cytokines, and what is the other name for cytokine. Is it endocrine or paracrine
Secreted by CD4 T cells and others. Also called interleukins.
Produced transiently and locally : paracrine/autocrine
What are the sickness behaviours promoted by immune cytokines like IL1- due to its affect on the nervous system
Early immune response: Temperature rising, pain and touch sensitivity, desire to sleep and be nurtured, catastrophising perceptions changing
What are the benefits of these sickness behaviours
help to conserve energy for the immune response and limits social spread of disease to increase survival of species
What are some pathologies related to the adaptive immune system
Allergy: hypersensitivity to innocuous antigens due to strong IgE antibody response
Autoimmunity: damage to own tissues due to reaction to self antigens
Cross reactivity: immune response against self antigens due to similarities in structure to antigen of pathogen
graft rejection
What causes vascular inflammation: vasculitis
Antigen/antibody complexes produced in high concentrations during infection lodge themselves in capillaries activate complement system and cause vascular damage–> leading to malar rash
What is Hashimotos thyroditis
autoimmune disease against thryoid antigens, destroying thyroid gland
What is Pernicious Anaemia
immmune system mediated damage to parietal cells of stomach compromises Vit b12 absobance
