Page 469 - Veterinary Immunology, 10th Edition

VetBooks.ir Hybridomas

The plasma cells in myelomas become neoplastic in an entirely
random manner, so the immunoglobulins that they secrete are not

usually directed against any antigen of practical importance.
Nevertheless, myeloma cells can be grown in tissue culture, where
they survive indefinitely. It is desirable to obtain large quantities of
absolutely pure, specific immunoglobulins directed against an
antigen of interest. This can be done by fusing normal plasma cells

making the antibody of interest with myeloma cells that can grow
in tissue culture. The resulting mixed cell is called a hybridoma.
The first stage in making a hybridoma is to generate antibody-

producing plasma cells (Fig. 15.24). This is done by immunizing a
mouse against the antigen of interest and repeating the process
several times to ensure that a good antibody response is mounted.
Two to four days after the antigen is administered, the spleen is
removed and broken up to form a cell suspension. These spleen

cells are suspended in culture medium, together with cultured
mouse myeloma cells. Generally, myeloma cells that do not secrete
immunoglobulins are used since this simplifies purification later

on. Polyethylene glycol is added to the mixture. This compound
induces many of the cells to fuse (although it takes about 200,000
spleen cells on average to form a viable hybrid with one myeloma
cell). If the fused cell mixture is cultured for several days, any
unfused spleen cells will die. The myeloma cells would normally

survive, but they are eliminated by blocking their nucleic acid
synthesis.

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