produce a large culture of antibody-producing cells and then to select from the culture only the clones of those cells that make the specific antibodies against the antigens found on the surface of the cancer cell being treated.
How the Clones Are Made Live human cancer cells carry the antigens that are going to be the targets for the antibodies. So the cancer cells (or their tumor-specific antigens alone) are injected into mice. The immune systems of the mice are activated, and the mice produce lymphocyte colonies in their spleens. Each of these lymphocytes has reacted to an antigen from the cancer cell. These activated B lymphocytes are then removed from the spleens and "immortalized" by fusion with a special B cell . This produces a "hybridoma"—basically, a factory that can indefinitely manufacture antibodies against a specific antigen of the original cancer cell.
The Effect on Normal Cells One problem with monoclonal antibodies is that while many MAbs can be produced to recognize tumor-associated antigens, most tumor antigens are not specific for the tumors. This means that these antigens may also be found on some normal cells. This could create problems, but many antigens are found in large quantities on tumor cells and only in very limited amounts on normal cells. So an antibody designed to react against such an antigen will be able to destroy quite a few tumor cells without causing too much harm to normal cells.
