micro unit 10A - immunology: antibodies + humoral defenses (antigens + antibodies, types of acquired immunity, serum immunoglobulins)

antigen (immunogen, allergen, Ag)

any substance that causes antibody formation; can be a microbe, foreign material or “self" and usually made of a protein or large polysaccharides

what is an antigen made of?

protein or large polysaccharides

antibody (immunoglobulin, Ab, Ig)

protein made in response to an antigen; they recognize and bind to the Ag

what are other names for antigen?

immunogen, allergen, Ag

what are other names for antibody?

immunoglobulin, Ab, Ig

antigen-antibody reaction

Ab will attach to the Ag at a specific site

valence

number of Ags that will attach to Ab

active immunity

body makes its own Ab

if you have active immunity, what are ways you can acquire an antigen?

natural active, artificial active

natural active

come across the antigen naturally (i.e. cold viruses)

artifical active

antigen artifically introduced (i.e. MMR, DPT, Hib vaccines)

passive

Ab from an animal/human

if you have passive immunity, what are ways you can receive an antigen?

natural passive, artifical passive

natural passive

Ab goes from mother → infant (placental or colostrum)

artifical passive

Ab received via injection (antitoxin or rhogam)

serum electrophoresis

gamma globulin portion of the serum (liquid part of blood)

IgA (γA)

secretory antibody; can have 70,000 or 400,000 Daltons of molecular weight; it is found in the blood, mucous, saliva, tears, and colostrum; it is involved in the 1st and 3rd line of defense; 13% of the total antibodies in serum but higher in total secretions of the body; monomer in the blood but a dimer in secretions

IgA is a ________ antibody

secretory

IgA can have _________ or ________ Daltons of molecular weight

70,000 or 400,000

where is IgA found?

blood, mucous, tears, saliva, colostrum

which lines of defense is IgA involved in?

1st and 3rd

IgA makes up what % of the total antibodies in serum? is it higher or lower in secretions of the body?

13%; higher

IgA is a monomer in ______, but a ______ in secretions

blood; dimer

what is the only antibody that is found in secretions?

IgA

IgD (γD)

weighs 180,000 Daltons in molecular weight; internal marker on B lymphocytes; monomer; makes up 0.02% of total Ab

what antibody weighs 180,000 Daltons?

IgD

IgD is an _______ _______ on lymphocytes

internal marker

is IgD a monomer or a dimer?

monomer

IgD makes up what % of total Ab?

0.02%

IgE (γE)

known as the “allergic” antibody; has a molecular weight of 200,000 Daltons; involved in hypersensitivity or allergic reactions; makes up 0.002% of total Ab; monomer

what antibody is involved in hypersensitivity or allergic reactions?

IgE

what antibody weighs 200,000 Daltons?

IgE

IgE makes up what % of total Ab?

0.002%, it is the least abundant Ab

is IgE a monomer or dimer?

monomer

IgG (γG)

the circulatory Ab; weighs 160,000 Daltons; protects against microbes, triggers complement, increases phagocytosis, crosses fetal-placental membrane, 80% of total Ab; monomer

what Ab is known as the “circulatory Ab” and weighs 160,000 Daltons?

IgG

which antibody protects against microbes, triggers, complement, and increases phagocytosis?

IgG

which antibody crosses the fetal-placental membrane?

IgG

IgG makes up what % of total Ab?

80%, it is the most abundant in the body

is IgG a monomer or dimer?

monomer

what are the 5 immunoglobulins?

1) IgA

2) IgD

3) IgE

4) IgG

5) IgM

IgM (γM)

circulatory Ab; weighs 900,000 Daltons; 1st Ab to arrive in response to initial exposure to Ag; short-lived; CANNOT cross the fetal-placental membrane; 6% of total Ab; pentamer

what Ab is known as a “circulatory Ab” and weighs 900,000 Daltons?

IgM

which Ab is the heaviest?

IgM

what Ab is short-lived after its being the first to arrive after initial exposure to Ag?

IgM

what Ab cannot cross the fetal placental membrane?

IgM

IgM makes up what % of total Ab?

6%

is IgM a monomer or dimer?

neither, it’s a pentamer

antibody memory

anamnestic response

when measuring a level of antibody, we measure it as a ______

titer

after inital exposure, how long does it take to make IgM?

4-7 days

after initial exposure, how long does it take to make IgG?

10-17 days

do antibodies destroy the antigen?

no, there are other mechanisms that the body uses in tandem with antibodies

after secondary exposure, how long does it take to make IgG?

2-7 days with a much greater magnitude

on average, how long does it take to make an antibody?

~2 weeks

what is the purpose of boosters?

to jog the memory of the cells to form antibodies

antibodies are made of ___ polypeptide chains

4

the antigen-binding site is made up off what chains?

a heavy chain and a light chain

how do the heavy and light chains differ?

heavy: much longer and heavier

light: less amino acids, shorter in length, smaller, and lighter

antibodies have how many light chains and how many heavy chains?

2 light chains, 2 heavy chains

the 4 polypeptide chains are joined by ______ bonds to form a __ shape

disulfide; Y

what is the top part of the antibody called?

arms

what part of the antibody does an antigen bind to?

FAB

how much of an antibody has the SAME amino acid sequence?

3/4

arms of Y

FAB region (fragment of Ag binding)

FAB region

part where Ag binds, contains variable amino acid sequence, specific for Ag

stem of Y

FC region (fragment of cell binding)

FC region

constains constant amino acid sequence, binds to cells, proteins, or complement