(i) an antibody producing lymphocyte cell (e.g. a spleen cell of mouse immunized with red blood cells from sheep), and (ii) a single myeloma cell (bone marrow tumour cell) which is capable of multiplying indefinitely. These fused hybrid cells or hybridoma have the antibody producing capability inherited from lymphocytes and have the ability to grow continuously (immortal) like malignant cancer cells.

Following steps are involved in the production of monoclonal antibodies using hybridoma technology :

(i) Immunize a rabbit through repeated injection of a specific antigen for the production of specific antibody, facilitated due to proliferation of the desired B cells.

(ii) Produce tumours in a mouse or a rabbit.

(iii) From the above two types of animals, culture separately spleen cells (spleen cells are rich in B cells and T cells) that produce specific antibodies, and myeloma cells that produce tumours (the myeloma cell line used, is unusual in two ways; it has stopped synthesizing antibodies and it is a mutant called HGPRT that can not synthesize the enzyme hypoxanthine guanine phosphoribosyl transferase or HGPRT).

(v) Select the desired hybridoma for cloning and antibody production; this is facilitated by preparing single cell colonies that will grow and can be used for screening of antibody producing hybridomas ; only one in several hundred cell hybrids will produce antibodies of the desired specificity ; (vi) Culture selected hybridoma cells for the production of monoclonal antibodies in large quantity; these hybridoma cells may be frozen for future use and may also be injected in the body of an animal so that antibodies will be produced in the body and can be recovered later from the body fluid