Serum antibody profiling

It’s in our blood

A new type of quantitative serum-antibody profiling

When studying the immune response to a drug, a vaccine, or an antigen, established serological technologies, such as ELISA, only provide semi-quantitative outputs such as titer. This can determine the presence of antibodies in blood but lacks the ability to discriminate between a low concentration of strong-binding antibodies and a high concentration of weak-binding antibodies. With multi-step workflows classical serological assays are slow and difficult to develop for new antigens, and the titers obtained cannot be compared between laboratories.

We developed our Seroaffinity and Concentration (SAffCon) assay to overcome these challenges.

By directly measuring antibody affinity and concentration in clinical samples, without the need for purification, immobilization, and external calibrants, we provide universally comparable absolute results to enable accurate correlation of antibody properties with immunogenicity and clinical outcome.

How can we help?

We built our Fluidity One-M instrument with your challenges in mind. Our proprietary Microfluidic Diffusional Sizing (MDS) technology enables comprehensive characterization of immune responses directly from the biofluid itself. The smart assistant – Fluidity Insight – with advanced machine learning experiment guidance, will guide you through the experiment from initial data points to final result.

True size

Use of a fluorescently labeled target ensures high specificity for antibody affinity measurements in complex samples like serum.

True environment

MDS works with undiluted blood and serum. Eliminating dilution means you can identify antibodies even at low concentration.

True insights

Measure antibody affinity and concentration simultaneously. Distinguish between strong and weak binders, and gain deeper understanding into humoral immune responses.

Application Note

Determination of antibody affinities and concentrations directly in clinical samples

Learn how our SAffCon Assay helps effectively measure antibody affinity and concentration directly in clinical samples such as serum or plasma, providing truly quantitative insights into the immune response to infection, vaccination, inflammation, organ transplants, or new drugs.

True size

The binding affinity of SARS-CoV-2 for the natural cell receptor was determined by MDS using fluorescently tagged ACE2. The ACE2-spike complex was then used to confirm the neutralizing activity of antibodies by detecting their ability to displace ACE2. The neutralizing antibody was able to fully displace the labelled ACE2, as confirmed by the measured size of the mixture in the presence of high nanomolar antibody concentrations returning to that of free ACE2 alone.

Read more from the original article.

True environment

Organ rejection mediated by antibodies specific to the human leukocyte antigen (HLA) subtype present on the surface of donor organs is a major problem in the transplant field. The detection of donor specific antibodies (DSA) is complicated by HLA comprising a family of closely related variants with well-known potential for cross-reactive binding. Thus, discriminating between a low concentration of tight binders (DSA) and a high concentration of weak binders (cross-reactive) may be a major step forward in improving transplant outcomes.

Exactly this has been achieved by researchers in the Kosmoliaptsis lab, who used Microfluidic Diffusional Sizing directly on serum samples, without pre-incubation or pretreatment, to simultaneously determine binding affinity and concentration of anti-HLA antibodies. In their work, the ability to take measurements directly in serum was crucial, and carefully validated.

Read more from the original article.

True insights

A new serological assay that directly and simultaneously reveals affinity and concentration, the two fundamental properties of an antibody, was demonstrated by Aguzzi et al. They applied the assay to sera obtained from recovered SARS-CoV-2 patients and could directly see that the immune responses mounted were moderately weak, and that prolonged infection in hospitalized patients lead to increased antibody concentration but no appreciable change in affinity. Both observations point to weak affinity maturation that would not be revealed by traditional ELISA.

Read more from the original article.

Explore related publications

Study the mechanism of action of anti-Aβ antibodies

Antibody titers after vaccination in patients receiving anti-CD20 therapy such as rituximab are typically lower than those of healthy individuals. Priddey et al. extended this observation by determining the extent to which the lower titers observed are due to antibodies in these patients showing reduced affinity or reduced concentration and observed that concentration was the more significant factor. Furthermore, they observed that affinity maturation was impacted by rituximab treatment, as evidenced by a failure of multiple vaccinations to lead to improved affinity in this group.

Priddy, Ashley, et al. ” Microfluidic antibody profiling after repeated SARS-CoV-2 vaccination links antibody affinity and concentration to impaired immunity and variant escape in patients on anti-CD20 therapy” Frontiers in Immunology 14 (2024)

Rapidly characterize antibody affinity in solution

Monoclonal antibodies are widely employed in healthcare, and their rapid release during the COVID-19 epidemic was instrumental in saving lives of heavily infected individuals. The ability to rapidly determine antibody affinity is important throughout modern drug development workflows, and doing so in solution promises more biologically relevant results than immobilization based approaches. In this paper the affinity of a range of anti-SARS-CoV-2 antibodies are determined against wild-type, delta and omicron strains and placed in context of humoral responses of both individuals and a pooled serological standard.

Fiedler, Sebastian, et al. ” Serological fingerprints link antiviral activity of therapeutic antibodies to affinity and concentration” Scientific Reports 12 (2022): 19791

Fluidic Sciences Ltd