Tutorial to help you answer the question:

Monoclonal antibodies come from clones of B cells that produce a single antibody of known specificity. B cells will nor normally divide in the absence of antibody. The special trick that allowed monoclonal antibody-producing cells to be grown in culture was:

A.	Mice were immunized with antigen and T cells removed and grown in culture to produce antibody
B.	Mice were injected with antigen and B cells were fused with cancer cells, producing a hybrid cell line that can grow in culture yet still produce antibody against the antigen
C.	Antibodies were produced by isolating mRNA from immunized mice and translating the message for antibody in the laboratory
D.	Macrophages were isolated from immunized mice that would stimulate na•ve B cells to continue to divide in culture, allowing the production of monoclonal antibodies

Tutorial

Within the body B cells are signalled to divide only after they bind antigen. Additionally, B cells will not normally grow in culture. In the mid 1970's, scientists discovered a method for producing unlimited amounts of a single antibody.

Mice are immunized with an antigen, and B cells isolated from the blood. These cells are fused with cancer cells which grow continuously. Hybrid cells produce the antibody of the B cell, but can now grow in culture. The cells can be cloned or grown from single colonies and screened for specific antibody. Antibodies produced from these "hybridomas" are very useful in biology and medicine.