Types of Recombinant Drugs - Biotechnology and Your Health: Pharmaceutical Applications - page 58

and, useful or not, produces antibodies against it. These antibodies
capture the useful antibody, rendering it useless and sending it on
its way to destruction. So mouse monoclonal antibodies could not
be effectively injected over and over again.
Scientists have invented several ways to get past this problem.
The portions of the antibody protein that allow it to bind to a specific
chemical structure are very small bits located at one end. The rest of
the antibody molecule allows the antibody to work, directing cells
to remove the foreign molecule or cell or triggering the death of
an infecting bacterium or virus (Figure 4.5). Methods were devised to
isolate the genetic instructions for the targeting end of the mouse
monoclonal antibody and insert it into the genetic instructions for
a human antibody protein. This meant that only a very small bit
of the engineered, now “humanized,” antibody was not human,
and the monoclonal antibody would be much less likely to trigger an
immune response that would prevent it from being used repeatedly.
The genetic information to produce an antibody that was mostly
human could be inserted into an animal cell for manufacture.
Another solution was the development of methods to fuse human
antibody-forming cells with blood-cancer cells so that the mono-
clonal antibodies were not just humanized, but actually human.
Stop and Consider
What concerns do you have about humans creating new microorganisms
through genetic engineering?
Researchers are also testing minibodies —small pieces of anti-
bodies engineered to be produced in bacteria or animal cells.
Because of their small size, minibodies may be able do things to cells
that larger, bulky antibodies cannot do. Such a minibody has
recently been produced and tested in animals, and in the future may
help patients with certain kinds of bleeding disorders.