Lecture 13 Flashcards
total proportion of T cells in human blood, common cell surface markers and number of lymphocytes per microlitre
75%, CD3, 1500 leukocytes per microlitre
total proportion of helper T cells in human blood, unique cell surface marker and number of lymphocytes per microlitre
45%, CD4, 900 leukocytes per microlitre
total proportion of cytotoxic T cells in human blood, unique cell surface marker and number of lymphocytes per microlitre
30%, CD8, 600 leukocytes per microlitre
total proportion of B cells in human blood, unique cell surface marker and number of lymphocytes per microlitre
12%, CD19 or 20, 250 leukocytes per microlitre
total proportion of NK/ADCC cells in human blood, unique cell surface marker and number of lymphocytes per microlitre
15%, CD 16 or 56, 300 leukocytes per microlitre
What MHC Class receptor activates antigen-sensitive CD4 Helper T cells?
MHC Class 2
what are cytokines made of?
low molecular weight glycoproteins
function of cytokines
regulate the quality, amplitude and duration (acute or chronic) of immune and inflammatory reactions, and to influence behaviour
where are cytokines produced?
local to the site of injury (paracrine or autocrine, rather than endocrine) - produced transiently (for a short time only when needed)
what determines the action of a cytokine?
the concentration, presence of other cytokines, cell type responding, and history of the cell
are cytokines only produced by blood cell lineages?
no, some are produced by other cell types
what systems do cytokines affect, other than the immune system?
non-immune cellular and system behaviour (e.g. nervous system)
what cells produce the most cytokines?
CD4 Helper T cells
how are cytokines classified?
based on the role they perform
another name for innate response cytokines
pro-inflammatory cytokines
function of innate response cytokines
- promote inflammatory processes (increased production cytokines (affected body temperature and sleeping pattern) and chemokines (IL-8)) - e.g. production of antibodies, phagocytosis and inflammation, cytotoxicity
- limit tissue damage
- initiate immune mechanisms (e.g. IL-1 and TNF)
examples of adaptive response cytokines and their function
IL4 - controls B cell activation
Interferon-phi/IL-2 - controls T cell activation
two main types of CD4 Helper T cells, the cytokines that control them and what they’re important for
Th1 - IFNgamma - intracellular infections
Th2 - IL-4 - parasitic responses
function of chemokines (chemotactic cytokines)
promote neutrophil chemotaxis at sites of inflammation
IL-8
function of haematopoietic cytokines
stimulate the production of various classes of blood cells (neutrophils, erythrocytes, monocytes, lymphocytes) from bone marrow when needed (e.g. GM-CSF = granulocyte-macrophage-colony stimulating factor)
function of co-stimulator molecules
modulates the actions of lymphocytes when they recognise antigens
example of a co-stimulator pair, the corresponding signal 1 and 2’s and the result (pg 69)
- B7 (CD80 and 86 - on activated APC’s, i.e. only appears when the antigen presented on the MHC receptor is foreign and potentially dangerous) and CD28 (on T cells).
- Signal 1 = activation of TCR complex by antigen on MHC Class I or II
- Signal 2 = binding of co-stimulators B7 (CD80 & 86)
- Signal 1 + 2 = activation of T cell (clonal expansion)
TCR complex constitutes of what?
TCR, T cell, CD4/8
what’s a safety mechanism to prevent autoimmunity?
co-stimulators (e.g. B7 on APCs and CD28 on T cells) needing to bind to cause activation of the T cell, if this binding doesn’t occur then the T cell is paralysed - this is called anergy and protects the immune system from reacting against self. (lymphocyte must have B7, regardless of whether it has an antigen on the MHC class I/II structure
