Cellular and Humoral Immunity Flashcards
Viruses
few molecules, replicate within cells, rapid evolution
Bacteria
can live in extracellular space or within cells
Large parasites
live within body fluids or within gut - too big to be phagocytosed
Unicellular parasites
frequently live inside cells
Cellular immunity
immune mechanisms involving direct action of a cell to eliminate a pathogen (includes phagocytosis, NK cells and T cells)
Humoral immunity
immune mechanisms which are mediated by factors in the fluids. This includes soluble proteins such as antibodies which bind foreign molecules and the complement system which can form pores in membranes of pathogens
Innate immunity
respond within hours, limited and fixed specificity, identical response to primary and repeat infection - alerts adaptive
Adaptive immunity
respond within days, highly diverse specificity, repeat response faster than primary - effective cells from first response clonally expand and become memory cells
Innate immune cells
macrophages, neutrophils, eosinophils, basophils, mast cells, dendritic cells, NK cells
Adaptive immune cells
B cells, T cells
TCR/BCR
T/B Cell Receptor, very diverse, random generation by splicing together genes in the DNA
Autoimmunity
immune system attacking its own body
Lymph node
detects infection of tissue
Spleen
detects infection of blood
Lymphatic system
route to return fluid from tissues to blood, transports immune cells, pathogens and antigens from tissues to lymph nodes (activates T and B cells) - important in cancer metastasis
Lymph composition
like plasma, leukocytes
Linking innate to adaptive
innate cells undergo phagocytosis, return to lymph node, naïve T cells recognise MHC molecules, and replicate
T/B cell path
naïve T or B cell - Activated/effector T or B cell - Memory T or B cell
Antibody
soluble protein that binds foreign molecules (extracellular organisms and toxins), millions of different types, two heavy and two light chains, constant and variable regions, highly specific
Antibody isotypes
(eg. IgG, IgM, etc) heavy chain determines class or isotype, light chains are either kappa or lambda
Antibody actions
neutralisation, coating virus/bacteria to promote phagocytosis, activating pathways which lyse bacteria
Neutralisation
antibody binding to virus can block entry into cells, and can neutralise and precipitate bacterial toxins
Immune complex
two antigens bound to an antibody
IgM
first class of antibody produced, neutralises and activates complement, 10 binding sites in pentamer form
Complement
part of the innateimmune systemthat helps orcomplementsthe ability ofantibodiesandphagocyticcells to clearpathogensfrom an organism
IgG
major Ig in blood, crosses placenta, promotes neutralisation and opsonisation
Oponisation
the process by which a pathogen is marked for ingestion and eliminated by aphagocyte
IgA
present in tears, saliva, mucous, milk, protects mucous membranes and infants (monomer and dimer forms)
IgE
triggers release of histamine from mast cells, allergy and anti-helminth responses (kill parasites)
IgD
primarily B cell surface bound, no purpose found
Use of antibodies in medicine and science
identify the presence/measure levels of proteins (eg. In serum)
examine locations of proteins using flurescently-labelled antibodies and flurescence microscopy
identify particular types of cells (by binding to characteristic cell surface molecules)
affinity purify proteins (chromatography)
Immunoflurescence Microscopy
fluorophore attached to antibody, antibody attaches to antigen, fluorophore emits light when excited by laser
ELISA
Enzyme-Linked Immunosorbent Assay: used to detect concentration of a protein within a sample (enzyme added that causes a colour reaction
MHC I
binds with CD8, bound peptides derived from intracellular proteins (ie. Viral infection), includes microglobulin and a peptide binding cleft, expressed on all nucleated cells, HLA-A, HLA-B, HLA-C
MHC II
binds with CD4, bound peptides derived from extracellular proteins (ie. Extracellular bacteria), expression mainly restricted to B cells, macrophages, dendritic cells, and thymic epithelium, HLA-DR, HLA-DP, HLA-DQ
HLA
Human Leukocyte Antigen: the MHC complex in humans, different molecules in different humans, differences cause tissue transplant rejection
CD8 (cytotoxic) T cells
kill virally infected or tumour cells, release granules which induce apoptosis
CD4 (helper) T cells
activates macrophages, assists B cells in producing antibodies
Treg
Regulatory T cells: recognise MHC II and peptide, express CD4 marker, function to suppress immune response
NKT cells
Natural Killer T cells: recognise MHC-like molecule called CD1d with bound glycolipid, suppress or promote immunity
Gamma delta T cells
associated with epithelial surfaces, recognise MHC-like molecules, suppress immunity and promote wound healing
