Serum Proteins 3 Flashcards
why do we need an immune system?
Protection from • Bacteria • Viruses • Parasites • Fungi
what is innate immunity
Innate - the first line of defence to any ‘non-self’ invader. Innate responses act locally via phagocytes. Rapid Response. Includes
• physical barriers - skin and mucous epithelium
• secretions- tear ducts
• low pH in stomach
• Humoral responses - involves substances in the body fluids complement system
what is adaptive immunity
Adaptive – specific immune response to antigens usually involving antibodies
Adaptive responses are initiated in secondary lymphoid organs (lymph nodes and spleen)
what are the 3 pathways in the complement system
classical pathway
alternative pathway
MB-lectin pathway
what 3 things will activation achieve
recruitment of inflammatory cells
opsonization of pathogen
killing of pathogens
what does C3 Convertase do
C3 is inactive as a whole, so is split into C3a and C3b by C3 Convertase.
what happens in the classical pathway
First - antibody binds to pathogen
Then – the C1 complex binds to the Antibody
C1 complex serine protease activity is activated when in contact with invader bound antibody.
C1 acts on C2 and C4 to split them- part of each then join together to form an enzyme
describe the MBLectin Binding Pathway?
Mannose is a sugar found on the surface of bacteria to which C5 of the complement system binds
Binding results in activation of C5 which converts C3- C3a and C3b and the MAC is formed.
MBL pathway homologous to classical pathway
MBL forms complex with MASPs that structurally resembles C1 complex
Active MBL-bound MASP complex C4 + C2 zymogens
what protects human cell from lysis
Certain “factors” bind to C3b and prevent its action: • Decay accelerating factor (DAF) • Membrane cofactor protein (MCP) • Complement receptor 1 (CR1) • Factor H.
what is transferrin
The main Iron transporter in serum
A glycoprotein: sugars on surface
what does transferrin do
Binds Fe3+ (Ferric form).
Accepts 2 irons per molecule from dietary iron and circulates in blood
Transferrin is taken into iron needy cells via its receptor present on peripheral tissues
describe gamma Globulins and the acquired immune system
We are continually subject to attack by microorganisms and viruses.
The immune system identifies and destroys foreign invaders.
Two types of immunity have been distinguished:
- Cellular immunity: T cells (T-helper and T-cytotoxic cells)
- Humoral immunity: B cells which produce antibodies (Immunoglobulins)
An antigen is a molecule or pathogen capable of eliciting an immune response
The part of a foreign substance that is recognized by an antibody is called an epitope
Antibodies are gamma globulins; the major type is immunoglobulin-G (IgG)
there are 5 different types of immunoglobulin- what are they and how are hey classified
- IgG: Gamma H chain
- IgM: Mu H chain
- IgA: Alpha H chain
- IgD: Delta H chain
- IgE: Epsilon H chain
classified by differences in heavy chain
describe IgG
most common (75%) • activates compliment • good opsoniser (labelling) • placenta transfer • classical structure
describe IgM
3rd most common (5- 10%) • 1st to be made in fetus, • 1st to be made upon antigen challenge • pentameric structure. • 10 identical H chain, L chain, • high avidity. • good agglutination • activates compliment • does not cross placenta.
