Scientists use monoclonal antibodies to test for the presence of anabolic steroids in an athlete's urine. To produce monoclonal antibodies, a mouse lymphocyte is combined with a tumour cell. What type of cell is created when a mouse lymphocyte and a tumour cell combine?

The production of monoclonal antibodies involves fusing two types of cells to get the desired properties of both. 1. A **lymphocyte** (specifically, a B-lymphocyte) is taken from a mouse that has been injected with the target antigen (in this case, the anabolic steroid). This cell produces the specific antibody required. 2. A **myeloma cell** (a type of tumour cell) is used because it is "immortal" – it can divide and reproduce indefinitely in the lab. When these two cells are fused, they create a **hybridoma** cell. This hybrid cell has the ability to produce the specific antibody (from the lymphocyte) and the ability to divide endlessly (from the tumour cell), allowing for the large-scale production of identical (monoclonal) antibodies.