When an organism is infected, a number of cells, including plasma cells, produce antibodies responsible for attacking components of the infectious agent. This is called an immune response. Various techniques are used to isolate the different plasma cells responsible for each antibody (plasma cell clone). Monoclonal antibodies are obtained by combining a plasma cell clone that produces an antibody of interest with a cell that has the ability to divide rapidly. Monoclonal antibodies produced in this way can neutralize a specific protein.
For example, in the case of COVID-19, monoclonal antibodies such as bamlanivimab and sotrovimab target the so-called S protein of SARS-CoV-2 in order to prevent the virus from multiplying, while tocilizumab and sarilumab block the interleukin-6 receptor in order to reduce the inflammatory response.
It should be noted that monoclonal antibodies can be identified by their name, which always ends with “mab” (short for “monoclonal antibodies”).