30 Aug 2021
Issue #72: The monoclonal antibody story 3: Fund smart people for solutions and economic benefit
Once Kohler and Milstein had produced their first antigen-specific hybridomas, a next step was to subclone (#71) the myeloma fusion partner (for antigen-specific B cells) and clean up the act by getting rid of the irrelevant antibody (Igs) from the tumour line. That proved easy. Myelomas soon lose the capacity to make the Ig heavy (H) chains, then light (L) chains that combine to form the two identical arms of the Y-shaped IgG molecule (#20). They soon had a spectrum of ‘immortalised hybridoma’ lines, each pumping-out loads of a single IgG molecule encoded by the DNA of just one antigen-specific B cell.
Relating these hybridoma-produced monoclonal antibodies (mAbs) back to our normal immune response in COVID-19, the polyclonal IgGs specific for the SARS-CoV-2 spike protein RBD (receptor binding domain for our ACE2 molecules) that circulate in blood plasma are our principle immune protective molecules. These are made as monoclonal IgGs by a spectrum of plasma cells located in bone marrow. Each of these Ig-secreting plasma cell ‘factories’ is descended from an activated, RBD-specific B lymphocyte. And, once exhausted, the plasma cells are readily renewed from a pool of slow-dividing, memory B cells of that same clonal lineage.
Following vaccination in the arm, the B cell response develops by rapid clonal expansion (cell division) in the regional axillary lymph nodes of our armpit, with progeny B cells exiting (into the blood via efferent lymph) after 6-10 days to go everywhere in the body (#40-#42). Following the infection of an unvaccinated person, that response likely kicks off in the adenoids, tonsils and cervical and mediastinal (draining the lung) lymph nodes, the difference being that many of the IgGs made are likely useless re stopping infection as they target the other 28 proteins of SARS-CoV-2 that, unlike the vaccine spike RBD, are not known to be involved in virus neutralization. Maybe IgGs specific for these other proteins play a part in clearing up some of the virus debris as the infection is terminated and cells are destroyed (#21).
Both Cesar Milstein and Georges Kohler, who soon moved from Milstein’s MRC Cambridge laboratory back to the Basel Institute for Immunology, immediately understood that their hybridoma ‘surrogates’ (for plasma cells) allowed them to push forward and pursue Milstein’s original, intellectually-driven question (#70), the basis of antibody diversity and IgG affinity maturation (#22) in a polyclonal response. Of course, once you publish a discovery you lose control, so they quickly found themselves part of a global enterprise that advanced rapidly with technological breakthroughs in protein and DNA sequencing. Georges later moved again (to Freiburg) after accepting one of the best jobs in biomedical research, the Directorship of a Max Planck Institute. Sadly, he died much too young, before turning 50, while Milstein stayed in Cambridge until, at age 75, he also left us.
Apart from advancing Milstein and Kohler’s own academic interests, science-based entrepreneurs immediately realised that the mouse monoclonal antibodies (mAbs) would be of immense value for laboratory research. A major revolution in my life as a researcher came when we could just pay a few dollars – or get hold of a hybridoma line and grow it up – to access plentiful mAbs specific for the CD4 and CD8 molecules that mark ‘helper’ and killer T cells respectively. Prior to that there were a few painfully generated antibodies – produced by immunising other animals – that were, at best, accessed as a gift of a few microliters from colleagues. Now, we were able to use labelled (with fluorescein or some other ‘emitter’) mAbs that, when passed by the laser beam of a fluorescence-activated cell sorter would allow us to separate them into different ‘pots’ or even as single cells for further analysis (#34).
Beyond that, though we had a reasonable idea of what the CD4+ and CD8+ T cell subsets likely did in biology, our insights were essentially correlative based on separate types of experiments in mice and cell cultures. Now, by injecting large quantities of say, an anti-CD8 mAb we could deplete a mouse to see how taking out the ‘killer’ T cells (#34) modified the outcome of a subsequent virus challenge. More next week on the uses of mAbs as laboratory and diagnostic tools.
Back at the mAb beginnings, Kohler and Milstein immediately understood that they had ‘invented’ – the word used in patent applications – a revolutionary technology with enormous practical implication. But, though the relevant UK authorities were alerted to the need to patent the approach as soon as possible, they moved too slowly and missed out on securing rights over this major discovery that had been funded by the British MRC. Subsequently, however, stimulated partly by some harsh criticism from the ‘Iron Lady’ British PM Margaret Thatcher, the MRC did establish intellectual property (IP) rights by patenting a number of further developments in what was to become an immensely lucrative industry.
By 2007, the ‘marvellous mAbs‘ were earning companies some $US20.6 billion annually with, by 2021, the amount being six-fold higher. That’s why enlightened governments fund basic science. It’s smart strategy to support smart people. A few researchers squirreling away in a laboratory as they indulge their own curiosity can give rise to discoveries that are of immense benefit, both financially and for the promotion of human wellbeing. We’ll expand on this over the next week or two.