Single B cell screening is a powerful technique for isolating and generating antigen-specific monoclonal antibodies (mAbs). This method, often integrated with high-throughput platforms, allows for efficient detection of antibody secretion and rapid identification of lead clones, thereby accelerating antibody discovery, vaccine design, and the development of targeted therapies. Single B cell screening service offerings enhance the accessibility of this advanced technology, enabling researchers to obtain high-quality monoclonal antibodies with efficiency and precision. Single B cells are advantageous for its simplicity, as it requires only a small number of cells while maintaining a high efficiency in rapidly obtaining specific mAbs.1
Related: What Is Single B Cell Screening? A Fast, Efficient Path to Monoclonal Antibody Discovery
Single B cell screening is a monoclonal antibody discovery method that identifies and isolates individual B cells producing antibodies of interest. A B cell is a type of immune cell that can recognize a specific target, called an antigen. An antigen may be a viral protein, tumor-associated protein, receptor, toxin, or other molecule that the immune system can recognize. When a B cell responds to an antigen, it produces an antibody, which is a Y-shaped protein that can bind that target with specificity.
In single B cell screening, researchers isolate individual B cells, determine which ones recognize the target antigen, recover the antibody-coding genes from each selected cell, and express those antibody sequences recombinantly. In simple terms, the method finds the immune cells that already “know” how to bind a target, then converts their antibody information into monoclonal antibodies for further testing.
This approach is important because antibody discovery often requires both speed and diversity. Researchers may need to screen large numbers of candidates to find antibodies with the right binding profile, functional activity, epitope coverage, species cross-reactivity, developability, or sequence characteristics. Single B cell screening can support this by directly accessing naturally generated antibody repertoires from immunized animals, infected or vaccinated individuals, or specialized animal models.
Compared with traditional hybridoma technology, single B cell screening can reduce the dependence on cell fusion and long subcloning workflows. Hybridoma technology works by fusing short-lived antibody-secreting B cells with immortal myeloma cells, creating hybridoma clones that can be expanded and screened. This approach has been foundational for monoclonal antibody discovery, but it can be time-consuming and lower throughput because successful fusion events are relatively inefficient and clone screening requires multiple steps.
Compared with phage display, single B cell screening preserves antibodies derived from an in vivo immune response. Phage display is a powerful in vitro technology that displays antibody fragments on bacteriophages and selects binders from large libraries. However, single B cell-derived antibodies retain natural heavy-chain and light-chain pairing from the original B cell, which can be valuable when researchers want antibodies shaped by immune selection, affinity maturation, and native sequence context.
AbDrop™: Microfluidic-Based Single B Cell Screening Platform →
Although workflows vary depending on the species, antigen, B cell subset, and screening platform, single B cell screening generally follows a stepwise process:
For animal-derived antibody discovery, the process often begins with immunization. An animal is exposed to the antigen of interest to generate an immune response. The antigen may be a purified protein, peptide, cell-associated target, DNA-encoded antigen, or another immunogen format depending on the project.
For human antibody discovery, researchers may start from peripheral blood mononuclear cells, or PBMCs. PBMCs are immune cells collected from blood and include B cells, T cells, monocytes, and other immune cell populations. In this setting, B cells may come from vaccinated donors, infected or convalescent individuals, autoimmune disease cohorts, or other biologically relevant sample sources.
The next step is to isolate B cells from the sample. Depending on the project, researchers may focus on memory B cells, plasmablasts, plasma cells, germinal center B cells, or broader B cell populations. Memory B cells are antigen-experienced B cells that carry membrane-bound antibodies known as B cell receptors, or BCRs. Plasma cells and plasmablasts are antibody-secreting cells, meaning they actively release soluble antibodies.
Antigen-specific B cells can be enriched using methods such as flow cytometry or microfluidics.
Flow cytometry is a technique that analyzes cells one by one as they pass through a laser-based detector. Fluorescent labels are used to identify specific cell markers or binding events. Fluorescence-activated cell sorting, or FACS, is a related method that physically separates selected cells based on fluorescence signals. In single B cell screening, an antigen can be labeled with a fluorescent dye and used as “bait” to detect B cells whose BCR binds the antigen.
Microfluidics is another important approach. Microfluidic systems handle extremely small fluid volumes and can compartmentalize single cells into tiny chambers, wells, or droplets. Droplet-based microfluidics can encapsulate individual B cells in water-in-oil droplets, creating small reaction compartments where secreted antibodies can be detected. This miniaturization can improve speed and throughput because antibody signals can build up faster in small volumes.
Other technologies may use antigen-coated beads, fluorescent detection reagents, Förster resonance energy transfer, or microwell-based assays. Some systems are “open,” meaning cells or reagents can be manipulated after loading, while others are “closed,” such as droplet-based systems where cells are enclosed until droplets are sorted or broken.
Once antigen-specific single B cells are identified, their antibody genes are recovered. Antibodies are made from heavy chains and light chains. The antigen-binding region depends on the variable heavy chain, often called VH, and the variable light chain, often called VL.
A key advantage of single B cell screening is that the natural heavy-light chain pair can be recovered from the same individual B cell. This is important because random pairing of heavy and light chains can change binding behavior. Preserving native VH–VL pairing helps maintain the original antibody specificity generated by the immune system.
The workflow usually involves reverse transcription, PCR amplification, and sequencing. Reverse transcription converts RNA into complementary DNA, or cDNA, which can then be amplified and sequenced. The recovered VH and VL sequences can be cloned into expression vectors.
After sequencing, selected antibody genes are expressed recombinantly, often in mammalian expression systems. The resulting monoclonal antibodies can then be tested for binding, specificity, affinity, function, cross-reactivity, and developability. Typical validation assays may include ELISA, flow cytometry-based binding, biolayer interferometry, surface plasmon resonance, cell-based assays, neutralization assays, SDS-PAGE, and SEC-HPLC, depending on the project goals.
Single B cell screening is often valued for its speed because it can bypass several bottlenecks associated with conventional hybridoma workflows. In hybridoma development, B cells must be fused with myeloma cells, selected, cloned, screened, expanded, and often subcloned again to confirm monoclonality. This can extend discovery timelines substantially.
Single B cell workflows instead aim to identify antigen-specific cells directly, recover antibody sequences, and express recombinant antibodies for downstream testing. This can accelerate the transition from immune response to sequence-defined antibody candidates.
The method is also efficient because it can interrogate large B cell populations. High-throughput screening is especially important when the desired antibodies are rare. A rare antibody may represent less than 0.1% of the relevant B cell population, meaning a low-throughput workflow may simply miss it. By screening large numbers of single B cells, researchers improve the chance of identifying uncommon binders with desirable profiles.
Single B cell screening is used across multiple areas of antibody research and therapeutic development.
In infectious disease research, single B cell screening can be used to isolate antibodies from immunized animals, vaccinated donors, infected individuals, or convalescent patients. This is especially useful when researchers need antibodies that recognize viral or bacterial antigens, neutralize pathogens, or bind conserved regions across strains.
Broadly neutralizing antibodies are a major example. These are antibodies that can neutralize multiple strains or variants of a pathogen. Because they may be rare within the immune repertoire, high-throughput single B cell approaches can be valuable for identifying them.
Monoclonal antibodies are widely used in oncology, including checkpoint blockade, tumor-targeting antibodies, antibody-drug conjugates, bispecific antibodies, and immune cell engagers. Single B cell screening can support the discovery of antibodies against tumor-associated antigens, cell-surface receptors, and other cancer-relevant targets.
For cancer antibody discovery, target presentation can be especially important. Some antigens are difficult to express in a soluble form or may adopt different conformations on the cell surface. Depending on the platform, screening strategies may use soluble antigens, antigen-expressing cells, or other formats to better reflect the biologically relevant target structure.
Single B cell analysis can help researchers understand immune responses after vaccination. By isolating antigen-specific B cells, scientists can study which antibody lineages are expanded, how much somatic hypermutation has occurred, and whether vaccination generates antibodies against protective epitopes.
Somatic hypermutation is a natural process in which B cells introduce mutations into antibody genes during immune responses. B cells producing antibodies with improved antigen binding can be preferentially selected, a process called affinity maturation. These concepts are central to vaccine research because they help explain how immune responses improve over time.
B cells are also involved in autoimmune diseases, where the immune system mistakenly targets the body’s own tissues. In some autoimmune settings, B cells may produce autoantibodies, present antigens to T cells, or contribute to inflammatory signaling.
Single B cell technologies can help researchers characterize autoreactive B cell populations, recover disease-associated antibody sequences, and study how B cell repertoires differ between healthy individuals and patients. This can support biomarker research, mechanism-of-disease studies, and therapeutic antibody discovery.
Biointron supports antibody discovery with a high-throughput single B cell screening platform designed to help researchers move from antigen-specific B cells to recombinant antibody candidates efficiently.
The platform integrates single B cell sorting, antibody sequence recovery, recombinant antibody expression, and downstream validation. This workflow is useful for projects where speed, candidate diversity, and native heavy-light chain pairing are important.
Biointron’s AbDrop™ platform is a droplet-based microfluidic single B cell screening system. The workflow can include animal immunization, B cell enrichment, droplet formation, single-cell loading and culturing, antigen-specific B cell labeling, single-cell sorting, single B cell sequencing, antibody expression, and validation. The platform can support multiple model systems, including mouse, rat, rabbit, transgenic, and humanized mouse models.
What makes single B cell screening faster than hybridoma-based methods?
Hybridoma-based antibody discovery requires fusion of B cells with myeloma cells, selection of fused cells, clone screening, expansion, and subcloning. Single B cell screening can identify antigen-specific B cells directly, recover antibody genes from individual cells, and move selected sequences into recombinant expression. This reduces reliance on cell fusion and long clone-generation workflows.
How does the single B cell sorting process ensure accuracy and reliability?
Accuracy depends on antigen design, appropriate controls, and validated sorting strategies. In flow cytometry-based workflows, fluorescently labeled antigens can be used to identify B cells that bind the target. Dual-labeling strategies may help distinguish true antigen-specific binders from nonspecific binding to fluorophores, tags, or other assay components. After sorting, antibody sequences are recovered from individual cells and expressed recombinantly, allowing binding and functional activity to be confirmed in follow-up assays.
Can this technique detect rare antibodies that are often missed by traditional approaches?
Yes, single B cell screening can improve the chance of finding rare antibodies because it can screen large numbers of individual B cells. This is especially useful when the desired binder is present at very low frequency, such as antibodies against conserved viral epitopes, difficult membrane proteins, or rare functional epitopes.
What sample sizes or starting materials are required for single B cell screening?
Starting materials depend on the project design and the source of B cells. Common starting materials include spleen, lymph nodes, bone marrow, peripheral blood mononuclear cells, plasmablasts, plasma cells, memory B cells, or B cells from immunized animals. Requirements vary by species, immune response strength, antigen type, and screening platform. For project planning, researchers should provide the antigen format, desired species or model, expected sample type, and intended downstream assays.
Single B cell screening provides a direct and efficient path from immune response to monoclonal antibody candidates. By isolating antigen-specific B cells, preserving native heavy-light chain pairing, and supporting high-throughput screening, the method helps researchers access antibody diversity that may be difficult to capture with slower or lower-throughput approaches.
For antibody discovery programs where rare binders, native sequence pairing, rapid expression, and reliable validation matter, single B cell screening offers a strong foundation. Biointron’s high-throughput single B cell screening platform supports this workflow with integrated sorting, sequencing, expression, and QC capabilities, helping researchers accelerate the path from target antigen to validated monoclonal antibody candidates.
AbDrop™: Microfluidic-Based Single B Cell Screening Platform →
Tiller, T. (2011). Single B cell antibody technologies. New Biotechnology, 28(5), 453-457. https://www.sciencedirect.com/science/article/pii/S1871678411000768
Pedrioli, A., & Oxenius, A. (2021). Single B Cell Technologies for monoclonal antibody discovery. Trends in Immunology, 42(12), 1143–1158. https://www.cell.com/trends/immunology/fulltext/S1471-4906(21)00213-1
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