Antibodies 1 Flashcards
function of immune system
protection against disease processes
immune sytem divided into
innate + adaptive
characteristics of adaptive system
- can specifically recognise foreign body
- ability to remember foreign body
- adapts its response to deal with new invaders
sub-divisions of adaptive system
- cellular - T lymphocytes
- humoral - B lymphocytes
T cells function + types
- mediate cellular immune response
- T helper
- T cytotoxic
- T regulatory
B cells function
mediate humoral immune system by producing antibodies
specificity of antigen recognition is achieved through…
antigen-binding receptors on surface of B & T cells
antigen binding receptors of T cells
T cell receptor
antigen binding receptors of B cells
immunoglobulin receptor cells
functions of antigen binding receptors
- recognise all pathogenic antigens
- initiate production of specific responses
where does antigen recognition occur?
secondary lymphoid organs
1 lymphocyte =
1 specificity
how does B lymphocytes produce antibody?
- binds to only 1 antigen + becomes activated
- activated B cell differentiates
- produces antibodies with same specificity
antibodies are Igs…
- secreted into circulation by B cells which binds antigen
- soluble, secreted Igs which are free floating in plasma
membrane-bound Igs
- antigen binding receptors on B cells surface
- not free floating in plasma
antibody basic structure
- polypeptide chains joined to form a Y shaped molecule
- 2 identical antigen binding sites
- flexible “hinge” region
what does flexible hinge region allow for?
wide range of distances between antigen binding sites
structural units of antibody
- 4 polypeptide chains
- 2 identical heavy “H” chains
- 2 identical light “L” chains
- held together by disulphide bonds
V & C regions
- V region - antibodies different parts of structure - variable
- C region - similar parts of antibody - constant
V & C regions of light and heavy chains
- light chains : half variable + half constant
- heavy chains : 1/4 variable + 3/4 constant
- variable regions from make up antigen binding sites
antibody: DOMAINS
- H&L chains fold into globular regions called domains
- each chain made of structural domain
- that fold into globular regions held by disulphide bonds
- L chains have 2 ; H chains have 4
- these form C&V regions
antibody : Fragments
- Igs cleaved at H region
- generates fragments - Fab + FC
- Fab - V + C regions ; binds antigen
- FC - C regions ; binds FC receptors on immune cells
antibody : classes
antibodies exhibit different versions of C region on H chains
five classes of antibodies
- IgG - gamma
- IgM - mu
- IgD - delta
- IgA - alpha
- IgE - epsilon
