Quiz 7: Animal Biotechnology
Myelomas are the antibody-secreting tumor cells, which secrete useful antibodies. Hybridoma technology is used to produce monoclonal antibodies by fusing myeloma cell with antibody-producing B cell. In addition, the myeloma cells provide rapidly dividing ability of the cell. They lack hypoxanthine-guanine phosphoribosyltransferase (HGPRT) gene; hence, they are sensitive to HAT medium. The fused myeloma cell and B lymphocytes are incubated in HAT medium, where unfused myeloma cells die because of absence of HGPRT. Furthermore, the unfused B lymphocytes die because of short life span. Ultimately, B cell-myeloma hybrids survive. These cells are able to produce antibodies (a property of B cell) and are immortal (property of myeloma cell). Hence, myeloma cells are known to provide immortality to cell culture.
The hybridoma cells obtained from mouse might evoke immune response in the human body. This is known as human anti-mouse antibody (HAMA) response. This HAMA response might occur because humans and mice sometimes make different antibody, for same antigen. This may cause rejection by human body. Hence, it is sometimes rejected by human immune system. The only solution to this problem is by making monoclonal antibodies more similar to human immune system.
Human anti-mouse antibody (HAMA) is known to evoke immune response in humans. To cope up with this problem, scientists have come out with a more precise technology, by using knock-in human genes. A monoclonal antibody named panitumab is produced by transgenic mice along with the knock-in human immune genes. This process involves inactivation of mouse immune response. It inactivates the ability of mouse to produce antibody in incorporating the concerned human gene into the deleted region of mouse gene. This process is mediated by homologous recombination. This experiment was does in the embryonic cells of mouse, which was later introduced into mouse embryos. The transgenic mouse produces human-like antibodies, which does not evoke immune response in humans.