Final answer:
B-lymphocytes, part of the immune system, are not fully differentiated cells. Upon activation by an antigen, they become plasma cells and produce antibodies. Through fusion with myeloma cells, hybridoma cells are created for continuous antibody production.
Step-by-step explanation:
These cells, which are not completely differentiated to produce antibody, are a part of the immune system and are involved in the humoral immune response. In the context of this discussion, the cells referred to are likely B-lymphocytes in a precursor or intermediate stage, before they become fully differentiated into plasma cells capable of producing antibodies.
B Cell Differentiation and Activation
B cells differentiate in the bone marrow. Initially, they generate up to 100 trillion different clones, encompassing a vast diversity of antigen receptors. These receptors enable B cells to recognize and bind to antigens. Upon activation by their antigen, B cells differentiate into plasma cells. Plasma cells, which are terminally differentiated cells, produce antibodies and do not maintain themselves for long, typically dying after a period of secretion. This is why they are not usually capable of growing in long-term cultures.
However, myeloma cells, which are cancerous B-lymphocytes, can grow indefinitely in cultures. By fusing a myeloma cell with an antibody-producing B cell, a hybridoma cell is created. Hybridoma cells combine the immortal growth characteristic of the myeloma with the antibody-producing ability of B cells, resulting in a cell line that can grow in culture and produce specific monoclonal antibodies (MAbs) indefinitely.