Hybridoma cells are a type of cell formed in culture for the preparation of monoclonal antibodies in clinical research. It is a fusion of myeloma cells, B lymphocytes, which are fused to form a cell that allows the nuclei of two different sources to express functions in the same cell, thus being able to produce what is needed in a directed manner, such as the preparation of monoclonal antibodies. Monoclonal antibodies are currently a very important source of drugs for the clinical treatment of many malignancies, such as monoclonal antibodies to CD20, also known as rituximab, which have a very important role in the treatment of many hematologic diseases, including lymphoma, as well as immune system diseases. In addition to rituximab, there are many other monoclonal antibodies against cell surface expressed antigens that are gradually being prepared for the treatment of a variety of diseases such as malignancies.