NEW YORK (Reuters Health) - Using a “gene farming approach,” investigators in Europe have produced large amounts of a bispecific biologically active recombinant antibody derivative (r28M) directed to melanoma cells and to CD28 receptors on T cells.
Such complex proteins are difficult to generate from bacterial or lower eukaryotic cell systems, Dr. Gottfried Brem, at the University of Veterinary Medicine in Vienna, Austria, and colleagues note. Even though they can be produced in mammalian cell culture, this approach is costly, laborious, and produces only small yields.
According to their report in the early online edition of the Proceedings of the National Academy of Sciences USA, therapeutic physiologic proteins, such as coagulation factors, can be harvested from the blood of mammals and are now being used clinically. They theorized that a similar approach could be used to manufacture more complex proteins, such as r28M.
They transfected bovine fetal fibroblasts with r28M, which were then used for nuclear transfer into enucleated oocytes that were implanted into recipient cows. Out of 77 blastocyst transfers into 31 recipients, there were 13 pregnancies and 11 calves were born alive and healthy.
According to the report, a transgenic protein that retained biological activity was isolated from serum at increasing concentrations during the first 9 postpartum months. The activity was similar to that of a standard protein preparation at concentrations of 0.05 to 0.1 g/liter.
Incubation of serum or purified recombinant antibody with cocultures of human peripheral blood monocytes and melanoma cells induced strong dose-dependent proliferation of CD28+ T cells that killed melanoma cells. Functional activity was maintained for months when stored at 4 degrees Centigrade.
“Having established a successful ‘gene farming’ procedure for the r28M protein, it should now be possible to evaluate its therapeutic potential in experimental clinical trials,” Dr. Brem’s group writes.
They conclude, “Future applications of transgene expression blood may extend the production of large quantities of additional Ig fusion proteins for diagnostic or therapeutic use.”
Source: Proc Natl Acad Sci USA 2004. [ Google search on this article ]
MeSH Headings:Animals, Laboratory: Animals, Transgenic: Cell Line: Cells, Cultured: Immunity, Cellular: Immunologic Techniques: Invertebrates: Lymphocyte Transformation: Investigative Techniques: Recombinant Fusion Proteins: Recombinant Proteins: Tumor Cells, Cultured: Drugs, Investigational: Organisms, Transgenic: Analytical, Diagnostic and Therapeutic Techniques and EquipmentCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
