Thoughts

Antibodies are blood proteins that kill cellular intruders (disease) - [1]
How do you culture antibodies? Via hybridomas - [2]
Once a hybridoma is produced, say for the COVID spike protein - then is mass production of it distributatable via basic DIY bio?
Are monoclonal antibodies safe? They naturally have to be tested, just like anything else. [3]
Once a hybridoma is available, does it produce reliable results? There is a process - [4]

Companies Working on It

GigaGen - [5] - uses single-cell sequencing to “capture and recreate” whole libraries of antibodies from recovered COVID-19 patients. The company can then choose which of those antibodies to turn into recombinant polyclonal antibody treatments
Regeneron - All coronaviruses have a cell surface protein called the spike protein. It helps the virus binds to the host cell for an infection. Regeneron’s SARS-CoV-2 antibodies will target the spike protein in an attempt to block the interaction of the virus with the host. - [6]

Antigen. [7] - ex: a virus.
Recombinant DNA - genetic engineering of DNA that does not yet exist in nature - [8]
Recombinant antibodies - [ecombinant antibodies are produced in vitro by cloning antibody genes for immune-specific heavy and light antibody chains into high-yield expression vectors - [9]
Serological (antibody) vs PCR tests for COVID - [10]
Convalescent serum - antibody-rich serum from blood of recovered patients - [11]. But convalescent sera are more effective for preventing disease rather than for treating disease. [12]