What does the term monoclonal refer to in immunology?

In immunology, the term monoclonal refers to antibodies that are produced by identical immune cells, which are clones of a single parent cell. This means that all the antibodies within that monoclonal population are identical in structure and specificity. Monoclonal antibodies are highly specific for particular antigens, allowing for targeted therapeutic and diagnostic applications.

Monoclonal antibodies are created in the laboratory by fusing a specific type of immune cell (usually a B cell) with a myeloma cell, resulting in hybrid cells known as hybridomas. These hybridomas can replicate indefinitely while producing the desired antibody that specifically reacts with a chosen antigen. This technology has numerous applications in research, clinical diagnostics, and treatments for various diseases, including some cancers and autoimmune conditions.

The other options do not correctly define monoclonal in the context of immunology. For instance, deriving from multiple immune cells would suggest a polyclonal response, which consists of a mixture of antibodies from different B cell lineages. Non-specific antibodies imply a lack of targeted specificity, which is contrary to the nature of monoclonal antibodies. Finally, the term monoclonal is not limited to natural infections but can be applied to laboratory-produced antibodies regardless of the source of the antigen