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Antigen presentation for B cells - Coggle Diagram
Antigen presentation for B cells
lgA
CHARACTERISTICS
Number of units
1 or 2
Activation of complement
Yes, by alternative pathway
Crosses placenta
No
Binds to phagocytes
No
Binds to lymphocytes
Yes
Binds to mast cells and basophils
No
Half-life (days) in serum
6
Percentage of total blood antibodies in serum
10
Location
Transport across epithelium
small amounts in blood
Larger amounts in body secretions such as
tears, milk, saliva,
and
mucus
and
attached
to the linings of the digestive, respiratory, and genitourinary systems.
consists of a single unit of two H and two L chains, but small amounts of dimers, trimers, and tetramers (2, 3, and 4 joined monomers) are present.
has an attached secretory component,
which protects the IgA from proteolytic (protein-splitting) enzymes and facilitates its transport.
does not cross the placenta, abundant in colostrum where it helps protect infants from intestinal pathogens.
lgA xde , ore cavities
lgG
main class of antibodies found in the blood
produced in largest quantities during a secondary response.
process
:
-The antigen-binding sites of IgG attach to antigens on microorganisms
-and their tissue-binding sites attach to receptors on phagocytic cells.
-Thus, as a microorganism is surrounded by IgG, a phagocytic cell is brought into position to engulf the organism.
-The tail section of the H chains also activates complement.
-lyse microorganisms and attract and stimulate phagocytes.
CHARACTERISTICS
Location
Serum, extravascular, and across placenta
Percentage of total blood antibodies in serum
75-85
Half-life (days) in serum
21
Binds to mast cells and basophils
No
Binds to lymphocytes
Yes
Binds to phagocytes
Yes
Crosses placenta
Yes
Activation of complement
Yes
Number of units
1
IgG is also found in milk and colostrum.
the only
immunoglobulin that can cross the placenta from mother to fetus and provide antibody protection for it.
lgM
CHARACTERISTICS
Number of units
5
Activation of complement
Yes, strongly
Crosses placenta
No
Binds to phagocytes
No
Binds to lymphocytes
Yes
Binds to mast cells and basophils
No
Half-life (days) in serum
5-10
Percentage of total blood antibodies in serum
5-10
Location
Serum and B cell membrane
found as a monomer on the surface of B cells
secreted as a pentamer by plasma cells.
inherited ABO blood types.
The first
antibody secreted into the blood during the early stages of a primary response.
consists of five units connected by their tails to a J chain and so has 10 peripheral antigen-binding sites
synthesized by the fetus
M stands for macromolecule (
BIG SIZE
)
unable to cross the placenta , mostly stays inside blood vessels.
High levels of IgM indicate
recent infection
or exposure to antigen.
lgE
CHARACTERISTICS
Number of units
1
Activation of complement
No
Crosses placenta
No
Binds to phagocytes
No
Binds to lymphocytes
Yes
Binds to mast cells and basophils
Yes
Half-life (days) in serum
2
Percentage of total blood antibodies in serum
0.005
Location
Serum and extracellular
reagin
has a special affinity for receptors on the plasma membranes of basophils in the blood or mast cells in the tissues.
It binds to these cells by tissue-binding sites, leaving antigen-binding sites free to bind antigens to which humans can develop allergies, such as drugs, pollens, and certain foods.
secrete various substances, such as histamine, which produces
allergy
symptoms.
Levels of IgE are elevated in patients with allergies and in those harboring worm parasites.
found mainly in body fluids and skin and is rare in blood. It has an extremely low concentration in serum.
lgD
found mainly on B-cell membranes and is rarely secreted.
function is unknown.
CHARACTERISTICS
Number of units
Activation of complement
No
Crosses placenta
no
Binds to phagocytes
no
Binds to lymphocytes
no
Binds to mast cells and basophils
no
Half-life (days) in serum
3
Percentage of total blood antibodies in serum
0.2
Location
Bcell membrane
may help initiate immune responses and some allergic reactions.
IgD levels rise in some autoimmune conditions.
