Antibody Engineering

By : Karla Mae M. ManaloBachelor of Arts in Mass Communication Major in

Journalism 2- A

Antibody

• A blood protein produced in response to and counteracting a specific antigen

Antibody Engineering

• antibodies are designed, assembled at the molecular level and utilized to achieve specific functions in biological systems

Two immunoglobulin • lg light chain • lg heavy chain

Antibody Engineering

– The Fc or Fab parts are manipulated for modifying binding affinity and specificity, while the Fc part is manipulated with the porpose of manipulating effector-functions of the antibody.

Papain

Fc

Fab

Antibody Generation

Figure 2-15 part 1 of 2

CDR1 and CDR2 CDR3

CDR1 and CDR2 CDR3

Xenotransplantation

Xenotransplantation

• Xenotransplantation refers to the practice of transplanting, implanting, or infusing living cells, tissues or organs from one species to another

• Concordant xenografting – transplantation between closely-related

animal species (baboon-to-human)

• Disconcordant xenografting:– Transplantation between distantly-

related species (pig-to-human)

• Pigs have larger organs• Pigs are already

slaughtered every day for meat

• Primates have smaller organs

• Primates share most of our genetic make up

• Primates are not available in numbers

Primates vs. Pigs

Types of Xenotransplant

Advantages

• It saves human lives.• It solves donor organ shortage.

History of Xenotransplantation

• 1682 – Bone from a dog was used in Russia in an attempt to repair his injured skull. This attempt was reported successful, but the Russian had the bone removed soon after surgery under threat of the church of excommunication.

• Late 1800’s – Frog skins were often used as a way of healing burns or skin ulcers by grafting said skin directly onto the patient’s skin.

• 1905 – French Surgeon grafts kidney tissues from a rabbit into a child, the child died two weeks later

• 1920 – Doctor Serge Voronoff transplanted tissues from the testicles of monkeys into older men, claiming that the procedure brought sexual rejuvenation.

• 1963-64 – Thomas Starzl grafts baboon kidneys into six patients. The patients only lasted between 19 and 98 days.

• 1963-64 – 12 patients received Chimpanzee kidneys , however, most failed within two months of the surgery, though one did live for nine months!

• 1964 – A 68-year-old man dies two hours after receiving a Chimpanzee heart.

• 1969-74 – Chimpanzee livers were transplanted into three children. They only survived between one to fourteen days.

• 1977 – A 25-year-old woman receives a baboon heart but dies only six hours after surgery. About the same time a 60-year-old man receives a chimpanzee heart to assist his own heart, but dies four days after.

History of Xenotransplantation

• 1984 – Baby Faye receives a baboon heart and dies 20 days later.

• 1992 – Using a four-drug “cocktail” to assist the transplantation of a baboon liver a patient lives for 71 days. However, the patient died of a brain hemorrhage and the type of rejection typical was not seen.

History of Xenotransplantation

• 1992 – A pig liver was placed besides the patients own liver in hopes that the extra liver would assist the patient’s liver long enough for a human donor to be found. The patient died after 32 hours.

• 1993 – Baboon marrow and kidney transplant, patient dies after 26 days.

• 1995 – Immune cells from a Baboon used for an AIDS patient. Condition improved though cells died quickly.

• 1997 – Pig fetal nerve cells used in patients with Parkinson’s disease. Pig cells survived in one patient for over 7 months

History of Xenotransplantation

• The Need for Organ Donors grows at 15% per year– about 60% of patients

awaiting replacement organs die on the waiting list

• 2004 Australia – In a survey two-thirds say they would use an animal organ to save their life– Survey shows 7 out of 10

males, and 6 out of 10 females would agree to xenotransplantation

Statistics

Biological Concepts

• Transplanted animal cells to be used for hemophillia, diabetes, Alzheimer’s and Parkinson’s disease

• Organ Transplants• A Way of delivering

genes of therapeutic importance

Modern Uses

Biological Concepts

• 25 known diseases can be contacted from pig to human

• Public Health risks• Perfection of

Cloning• Rejection rate is

higher

Existing Problems and Worries

Problems

• Rejection of the xenograft is thought to occur, since galactose -1,3-galactose is expressed by pig cells.

• Humans are known to produce antibodies against this protein

Solutions

• Interruption of the complement cascade• The recipient's complement cascade can be inhibited through the use of cobra venom factor (which depletes C3), soluble complement receptor type 1, anti-C5 antibodies, or C1 inhibitor (C1-INH)

Solutions• Transgenic organs (Gen engineered pigs)

– 1,3 galactosyl transferase gene knockouts – deletion of gene which codes for the enzyme responsible for expression of the immunogeneic gal-α-1,3 Gal moiety

– Increased expression of H-transferase (α 1,2 fucosyltransferase), an enzyme that competes with galactosyl transferase

– Expression of human complement regulators (CD55, CD46, and CD59) to inhibit the complement cascade

Ethical Issues

• Jewish – Forbidden to eat any part of a pig

• Heart is the seat of the soul

• No hybridization of man with any other species

Religion

Ethical Issues

• Physical discomfort• Psychological

discomfort• Why should

animals suffer for humans?

• The right to life

Animal Rights

Ethical Issues

• Bible technicalities• Importance of

human life• Pigs are already

slaughtered daily• Use as few

primates as possible

Arguments For Xenotransplantation