Download Monoclonal Antibodies

Monoclonal Antibodies
Monoclonal antibodies (mAb) are antibodies that are
identical because they were produced by one type of
immune cell, all clones of a single parent cell.
Polyclonal antibodies are antibodies that are
derived from different cell lines.
• Antibodies have important uses beyond fighting
infections in the body.
• Production of long-lasting monoclonal antibodies is a
recent invention and it is used in both medicine and
research.
• Monoclonal Antibody: a stable antibody which can
be used over a period of time
Producing Monoclonal Antibodies
1. Inject a mouse with a specific antigen to
stimulate its immune system to produce
necessary antibodies.
2. Extract mouse spleen cells (containing Blymphocytes) and culture them in the lab.
3. Extract mouse tumour cells, which grow
continuously, and culture them in the lab.
4. Mix spleen cells and tumour cells on the
same plate and culture.
Producing Monoclonal Antibodies
5. Add polyethylene glycol – this causes some Blymphocytes to fuse with tumour cells to
produce a hybrid cell called a hybridoma.
6. Grow the cells under conditions that allow only
hybridoma cells to survive.
7. Extract the cells, culture them separately and
test the medium around each cell for the
specific antibody of interest.
8. Culture the cells making the desired antibody
and use as needed.
The types of mAb designed
A. Murine source mAbs: rodent mAbs with excellent affinities
and specificities, generated using conventional hydrioma
technology. Clinical efficacy compromised by HAMA(human
anti murine antibody) response, which lead to allergic or
immune complex herpersensitivities.
B. Chimeric mAbs: chimers combine the human constant regions
with the intact rodent variable regions. Affinity and specificity
unchanged. Also cause human antichimeric antibody
response (30% murine resource)
C. Humanized mAbs: contained only the small part the rodent
variable region grafted onto human variable region
framework
Evolution of Therapeutic
Antibodies
Treatment of Cancer
• Cancer cells carry specific tumour-associated
antigens (TAA) on their plasma membrane.
• Monoclonal anti-TAA antibodies have been
produced.
• Drugs which kill tumour cells or inhibit key
proteins in tumour cells are attached to
monoclonal anti-TAA antibodies.
• Cancer cells are specifically targeted, avoiding
damage to healthy host cells.
Three mechanisms that could be responsible for the
cancer treatment.
A. mAbs act directly when binding to a cancer specific
antigens and induce immunological response to
cancer cells. Such as inducing cancer cell apoptosis,
inhibiting growth, or interfering with a key
function.
B. mAbs was modified for delivery of a toxin,
radioisotope, cytokine or other active conjugates.
C. it is also possible to design bispecific antibodies
that can bind with their Fab regions both to target
mAbs treatment for cancer cells
ADEPT, antibody directed enzyme prodrug therapy; ADCC, antibody
dependent cell-mediated cytotoxicity; CDC, complement dependent
cytotoxicity; MAb, monoclonal antibody; scFv, single-chain Fv fragment.
Problems…
• Many patients develop immune response to
monoclonal antibodies produced in mice, as
these are foreign proteins.
• Genetically engineered antibodies are being
perfected to avoid triggering immune
response.