Microfluidic Method Identifies Rare Antibodies with Therapeutic Potential

A novel microfluidic platform, able to rapidly isolate and identify rare antibodies from a vast repertoire of human B cells, has been developed by scientists. Their findings were published in Communications Biology. This technology could possess the ability to support and enhance the development of novel vaccines and biopharmaceuticals in the future.

Background

Antibodies with high potency have recently been identified in humans, with therapeutic potential against several conditions including cancer, autoimmune disease, and microbial infection.¹ These ‘potent antibodies’ have the potential to become powerful immunotherapies and are also thought to be less immunogenic than the ‘more traditional’ rodent-engineered antibodies,² However, the B cells responsible for producing these attractive antibodies are rare in convalescent individuals. There has been a distinct lack of tools able to identify these B cells, making it difficult to harness the therapeutic potential of this antibody type — until now.

“In comparison to antibodies matured in mice or rats, human-derived antibodies may be best-suited to treat human disease.” Explained, Sarav Rajan, Scientist, Antibody Discovery & Protein Engineering, MedImmune, first author of the study.

Method and Findings

Using their microfluidic platform, the researchers were able to encapsulate 1 million individual B cells inside distinct microscopic water droplets in <1 hour. This technique meant they were able to identify and purify antigen-specific antibodies within just 1 month.

“Applying microfluidics to biology is fairly new, even more so using it for single-cell capture, but we can see momentum building in this space.” Said Rajan.


From millions of cells, VH and VL transcripts were amplified and paired, resulting in an ‘expression-ready’ single-chain variable fragment (scFv) library. Once generated, this library was applied to multiple technologies including; high-throughput screening, phage-display, and next generation sequencing, enabling the researchers to “enrich for antigen-specific clones”.¹ The team screened healthy individual’s B cell repertoires to identify antibodies able to bind influenza hemagglutinin (HA). These antibodies were then selected to feature in a cross-reactive panel. Seven monoclonal antibodies within this panel displayed broad reactivity, targeting different, clinically relevant influenza HA subtypes.

Future Implications

The authors emphasized that this is one of the most efficient and robust methods for the discovery of antibodies originating from natural human repertoires They also stressed its potential value for fighting Ebola, Zika, and other emerging infectious diseases.

Rajan commented: “Since we capture the repertoire in DNA form, which is very stable, we envision [that] generating libraries from many individuals can be archived, scaled-up, merged and screened for binding to any number of targets. We also hope that the speed at which antibodies are discovered with this approach would make it well-suited for discovery campaigns to combat emerging infections as they appear.”

Projects such as the Human Immunome Program, along with other large-scale NGS initiatives, could also benefit.¹

Rajan also highlighted the technology’s potential within the field of vaccinology: “The technology may also facilitate rational vaccine design. The ability to identify antibodies binding to shared epitopes, for instance against multiple viral subtypes, is often sought out in the field, as they could point to a way of creating vaccines with broader coverage.”

The authors believe that the method could be widely adopted as the price of equipment used in the project was “well within the reach of most laboratories”. The application of this technology is not limited to the detection of human antibodies and can be used to isolate antibodies from other species, provided they their V-gene sequence information is available.

“We hope the approach will facilitate the mining of natural antibodies from humans in response to disease. While we've highlighted the application of the technology in infectious disease therapy, it's known that antibodies are involved in other diseases, including cancer, and it will be interesting to see how such a method could accelerate discovery in these areas.” Concluded Rajan.

Sarav Rajan was speaking to Laura Elizabeth Mason, Science Writer for Technology Networks.

References

1. Rajan S, Kierny, MR, Mercer A, Wu J, Tovchigrechko A, Wu H, Dall ′Acqua WF, Xiao X, Chowdhury PS. Recombinant human B cell repertoires enable screening for rare, specific, and natively paired antibodies. Comms Bio. 2018. doi: 10.1038/s42003-017-0006-2