Antibody structure and function Flashcards
Stimulated B cell gives rise to…
Antibody secreting plasma cells
What are the functions of gammaglobulin (Antibody)? 
-neutralization
-Opsonization (Enhances phagocytosis)
-Complement activation (Triggers compliment activity)
-Antibody dependent cell mediated cytotoxicity (ADCC) 
This is where cells (NK cells, macrophages, neutrophils) Recognize anybody bound to target sell and release substances to destroy Target cell
Antibody dependent cell mediated cytotoxicity (ADCC) 
What are the classes (Isotypes) Of anybody? 
IgM, IgG, IgA, IgE, IgD
 antibodies appear primarily in the ____________ band with serum Electrophoresis at pH ______. 
gamma (y), 8.6
Gammaglobulin is enriched with….
Antibody
L chains are secreted by….
What are the two types?
Malignant plasma cells
-Kappa (k)
-Lambda 
 what are the two regions of light chains?
They contain between _______ and ______ amino acids. 
Constant region and variable region
200-220
What is the heavy chains composed of?
Variable region and Constant region
110 Amino acids variable
Remaining amino acids for constant
Heavy chains have three or more regions with very similar sequences designated…
CH1, CH2, and CH3
Heavy chains are _________ to each class and give each immunoglobulin its name. 
Unique
Heavy chains:
A unique amino acid sequence that is common to all immunoglobulin molecules of a given class in a given species
Isotype
Heavy chains:
Minor variations of isotype sequences that are present in some individuals but not others
Allotypes 
Heavy chains:
Variation in variable regions that give individual antibody molecule specificity
idiotype
Fab (fragment antigen binding) Antibodies specificity Is associated with what region? 
Variable region (Antigen binding site)
Fc (fraction crystallized) Antibody function Is associated with what region? 
Constant region (Effecter function)
What is the clinical usefulness of Fab fragments?
-neutralizing antibodies (Rattlesnake venom, Digoxin Overdose)
-Small and passed through the kidneys, eliminated in urine
What do antibodies are found in monomers?
IgG and IgE
What antibodies can be found in multimers held together by J-chain?
IgM: pentimers and monomers
IgA: dimers and monomers
B cell receptor ___________ with Membrane component
Monomeric
What is the predominant immunoglobulin in humans?
IgG
75-80% of total serum immunoglobulins
Which immunoglobulin has the longest half-life of any class?
IgG (23 days) 
Wish antibody can cross the placenta?
IgG
What are the functions of IgG? 
-fixing compliment
-Coating antigen for enhance phagocytosis (Opsonization)
- binding to cells for antibody dependent cellular Cytotoxicity (ADCC) by NK and other cells
-Neutralizing toxins and viruses
-Participating in agglutination and precipitation reaction
Macrophages, monocytes, and neutrophils have ____ Receptors specific to the ____  region of IgG, Increasing the efficacy of phagocytosis
Fc, Fc
What allows IgG to enter extravascular spaces more readily than other immunoglobulin types?
A high diffusion coefficient
______ plays a major role in neutralization Of toxins and viruses
IgG
This is known as a macroglobulin and has a molecular weight of about 900,000 Da
IgM
Accounts for 5 to 10% of all serum immunoglobulins
IgM
Has a half-life of six days
IgM
IGN can exist as a
___________ (on Surface of the cells)
___________ (Found in secretions)
Monomer
Pentamer
The Pentamer form of IgM is held together by _____ chains, which are linkage points for disulfide bonds between two adjacent monomers
J
IgM pentamer has a starlike shape with ______  antigen binding sites
10
- has a high valency 
Immunoglobulin found mainly in the intravascular pool. Cannot cross the placenta. 
IgM
Known as a primary response in a body
-Appears first after antigenic stimulation in the maturing infant
-synthesized only as long as antigen remains present
-no memory cells
IgM
Where are the functions of IgM?
-complement fixation
-Help with opsonization due to its ability to activate compliment (Some compliment components are opsonins like C3b)
-Agglutination
-Toxin neutralization
Accounts for 10 to 15% of all circulating amino goblins in serum
IgA
-One variable and three constant regions
-monomer with a molecular weight of approximately 1600,000 
IgA
Antibody that is synthesized in plasma cells found mainly in mucosal associated lymphoid tissue and beneath mucosal epithelium
Secretory IgA 
Secretory IgA is Released in what form?
Dimeric
-it is captured by Poly-Ig Receptor which transports it across epithelial cells
-When released, the IgA Has part of the poly-lg Receptors still attached.
-The part derive from receptor remaining is called secretary component (SC) 
What are the functions of secretary IgA? 
-patrols mucosal services and acts as a first line of defense
-Neutralizes toxins produced by microorganisms
-Prevent bacterial adherence to mucosal surfaces
- Found in breastmilk and possibly transfers immunity to newborn during breast-feeding
- Complexes of IGA an antigen are easily trapped in mucus and illuminated by the ciliated epithelial cells of the respiratory and intestinal tracta
-Aggregation of IGA immune complex is may trigger the alternate complement system

What are the proportions of IgD?
Extremely scarce in the serum
Found on the surface of immunocompetent but unstimulated be lymphocytes
IgD
Appears second after IgM 
IgD
-May play a role in the cell activation
-Plays a role in regulating the cell maturation and differentiation
IgD
Secreted form and serum does not appear to serve a protective function. Does not bind complement, does not bind neutrophils or macrophages, does not cross the placenta.
IgD
.0005% of total serum immunoglobulin
IgE
-Produced by plasma cells that are located primarily in the lungs, gut and skin
-does not participate in complement fixation, agglutination or opsonization
-Incapable of crossing the placenta
IgE
Attaches to basophils, eosinophils, and tissue mast cells through high-affinity Fcę and RI Receptors
IgE
Two adjacent _________ molecules on a mast cell bind a specific antigen
IgE
-Cascade of cellular events result in degranulation of massage and release of vasoactive amines such as histamine and heparin
-induce allergic type reactions
-Helps expel parasites
IgE
Type one immediate hypersensitivity results in….
Hey fever, asthma, vomiting and diarrhea, hives, life-threatening anaphylactic shock
What antibody causes type one immediate hypersensitivity?
IgE allergic reactions
_______________ play a major part In the destruction of large antigens, such as parasitic worms, that cannot be easily phagocytized 
Eosinophils
B cell receptor antibody monomer has _______________ anchor 
Transmembrane
- Ig beta an Ig alpha transmit signal
B cell receptor can have heavy chains from….
Any of the antibody classes
-Doesn’t matter what the class, B cell receptors still a monomer
Antigen binding site is composed of….
Both heavy and light chain segments
-Variable regions of each chain form this site
T cells recognize ___________ epitopes/peptides
Linear
Binding strength between an antibody and a single antigenic determinate
affinity
High affinity: tightly bind antigen at lower concentration
Low affinity: better when a large amount of antigen is present
Number of antibody combining sites and the number of epitopes in a single antigen
Avidity
Antibodies that are mainly used for diagnostic testing and therapeutic purposes
-Delivery of therapeutic agents in diseases
Monoclonal antibodies
Develop based on knowledge that B cells are genetically preprogramed to synthesize very specific antibodies
-are derived from a single parent antibody producing cell that has reproduced many times
Monoclonal antibodies
