Reading the writing of immunizations in mice – the quantitative assessment of secreted antibodies to evaluate the quality of immunizations

Abstract

Abstract Vaccination needs to prepare the immune system to rapidly secrete specific antibodies upon a future encounter with the pathogen. Assessments of this feature are often challenging to perform, as measurements using antibody titers represent only a poorly resolved average of the rapidly evolving repertoire. We recently published and described a novel, droplet-based microfluidic technology that allows the quantitative characterization of humoral immune responses with single-cell and -antibody resolution. The employed snapshot analysis in this system enables studying even rapidly evolving repertoires. Additionally, the method extracts for each secreted antibody its production rate, specificity, and affinity, offering a high-resolution view of immunization. Consequently, this system enables the investigation of the immunization-generated secreted antibody repertoire with high temporal, analytical, and spatial resolution. This study in mice used the above method to characterize the quality of the immunization-induced immunoglobulin-G repertoire, and we correlated these measures with the recall-accessible repertoire. Here, we showed that introducing variation in the immunization schemes led to significant differences in the secreted repertoire. Additional analysis after recall allowed quantifying the accessible antibody repertoire, and due to the single-cell resolution, our data allowed us to compare these two repertoires on a phenotypical level. We showed that the relationships between the two repertoires are not trivial and strongly depend on immunization itself. In summary, the developed approach introduced a novel, quantitative, and functionally resolved alternative to study the quality of immunizations.