Group 2 students - Wajjiha Amjad, Ayesha Ishtiaq, Sheeza Arif, and Shabana Noor - submitted a report on antibodies to Dr. Sadaf. The report defines antibodies and discusses their structure, including heavy and light chains that form a Y-shape. It also describes how antibodies bind to antigens and the variable and constant regions that determine specificity and effector functions. Furthermore, it explains how somatic hypermutation and VDJ recombination increase antibody diversity to target the wide range of pathogens encountered. The report concludes that monoclonal antibodies are better for therapeutic applications while polyclonal antibodies are generally preferable for research due to advantages in tolerance and epitope recognition.

1. Group 2
Wajjiha Amjad 1378-FBAS/BSBT/F20
Ayesha Ishtiaq 1383-FBAS/BSBT/F20
Sheeza Arif 1386-FBAS/BSBT/F20
Shabana Noor 1399-
FBAS/BSBT/F20
Submitted to: Dr. Sadaf
Submission date: October 18, 2022

2. • A protein made by plasma cells (a type of white blood
cell) in response to an antigen (a substance that causes
the body to make a specific immune response).
• Each antibody can bind to only one specific antigen. The
purpose of this binding is to help destroy the antigen.
• anti- "against" + body.
Antibody:

3. Structure of Antibody
• Each antibody consists of four polypeptides– two heavy
chains and two light chains joined to form a "Y" shaped
molecule.
• The amino acid sequence in the tips of the "Y" varies greatly
among different antibodies.
• This variable region, composed of 110 -130 amino acids, give
the antibody its specificity for binding antigen.
• The variable region includes the ends of the light and heavy
chains.

4. • Treating the antibody with a protease can cleave this region,
producing Fab or fragment antigen binding that include the
variable ends of an antibody.
• The constant region determines the mechanism used to
destroy antigen.
• The variable region is further subdivided into hypervariable
(HV) and framework (FR) regions.
• Hypervariable regions have a high ratio of different amino
acids in a given position, relative to the most common amino
acid in that position.

6. • Within light and heavy chains, three hypervariable regions exist
– HV 1, 2 and 3.
• Four FR regions which have more stable amino acids sequences
separate the HV regions.
• The HV regions directly contact a portion of the antigen's
surface hence called complementarity determining regions, or
CDRs.
• The FR regions form a beta-sheet structure which serves as a
scaffold to hold the HV regions in position to contact antigen.

7. • There are millions of antigen/epitope.
• Our immune system has the ability to produce specific
antibody against specific antigens.
• This diversification in antibody is known as antibody
diversity.
• There are variety of pathogens entering in our body so we
should have huge collection of antibody.
• Two process that produce diversity and variety to the
antibody genes take place in germinal cell through B cell
maturation.

8. • Somatic cells contains a relatively small number of Ig genes.
• Somatic hyper-mutation means mutation is very active at
this variable region.
• At V region variation take place.
• Variable region of Ig chains is encoded by multiple gene
segments.
• These segments arrange to form a functional variable region
exons.
Somatic Hyper-mutation

9. • A process by which B cells randomly assemble Ig gene
segments to form functional variable region exon.
• Process occurs at the early development of
lymphocytes.
• Two types of recombination occurs one in V region and
one in C region.
• Recombination in C region gives the idea of what kind
of antibody will produce.
VDJ Recombination

10. • Recombination takes place in heavy and light chains.
• The V ( variable) region of L chain is coded by a one of the
V J recombinant.
• V region of H chain is coded by a one of the VDJ
recombinant.
• The C (Constant) region of both H & L chain is coded by
one of the C region of gene.
• In human there are 51Vh segments, 27Dh segments, 6Jh
segments and series of C region.

11. • V region is coded by 3 type of gene segments: V D & J
segments.
• V D J gene segments encode the variable domain of IG
heavy chain.
• During B cell maturation and somatic cell recombination
randomly selected D and J segments join and intervening
DNA is discarded.
• Next randomly selected V segment and DJ rearranged
segment joins and again intervening DNA is discarded.
VDJ recombination – heavy
chain gene family

12. • Heavy chain then reassembled to make Ig that is unique
to particular B cell and will fight against specific antigen.
• Recombination in C region gives the idea of what kind of
antibody will produce.
• The region present after V region antibody will name
after it.
M D G E A
V D J
Variable Region Constant Region
µ & γ E α

13. • No recombination , B cell keep producing Ig M.
• Ig M is most dominant form.
• First type of antibody produced when B cell is not
specific and don’t know specific antigens.
• Ig loci has multiple gene segments and these can be
rearranged in many possible ways combination.
• This leads to antibody diversity.

15. • Classification of antibodies is by the means in which they
are created from lymphocytes.
• The antibodies can be classified into two primary types:
Monoclonal
Antibodies:
Polyclonal
Antibodies:

16. Monoclonal Antibodies:
• Monoclonal Antibodies are generated by identical B-cells
which are clones from a single parent cell.
• mAbs have the monovalent affinity and only recognize the
same epitope of an antigen.
Polyclonal Antibodies:
• Polyclonal Antibodies are the antibodies usually
produced by different B-cell clones in the body.
• pAbs can bind to many epitopes of a single antigen.

18. Polyclonal Antibodies
(pAbs)
Monoclonal Antibodies
(mAbs)
Produced by different clones
of plasma B-cells.
A heterogeneous antibody
population
Produced by a single clone of
plasma B-cells.
A homogeneous antibody
population.
1.
2.
3.
Mixture of immunoglobulin
that are secreted against a
particular antigen.
A population of antibodies that
are produced by a single clone
of plasma B-cells.

19. Polyclonal Antibodies
(pAbs)
Monoclonal Antibodies
(mAbs)
Tolerant of small changes in
protien structure.
Interact with different
epitopes on the same antigen.
Intolerant to changes in
protein structure.
Interact with a particular
epitope on the antigen.
4.
5.
6.
Production doest not
required hybridoma cell
lines.
Production requires hybridoma
cell lines.

20. Conclusions
• Conclusively, For applications such as therapeutic drug
development that require large volumes of identical antibody
specific to a single epitope, monoclonal antibodies are a better
solution.
• For general research applications, however, the advantages of
polyclonal antibodies typically outweigh the few advantages
that monoclonal antibodies provide.
• With affinity purification of serum against small antigen
targets, the advantages of polyclonal antibodies are further
extended.