Activation, clonal expansion, and affinity maturation of antigen-specific B cells are considered the hallmarks of
adaptive immunity; hence, the assessment of B cell responses is thought to provide correlates of immune
protection. Antigen-specific B cell responses have traditionally been observed indirectly, through the study of
the magnitude of the serum antibody pool using ELISA. Direct measurements of antibody-secreting cells have
also been done using ELISPOT, or more recently by flow cytometry (FC). None of these methods, however,
provide a measure of a B cell’s overall binding avidity for its cognate antigen, despite the fact that this measure
is frequently acknowledged as prognostic of immune protection and may be critical for the evaluation of
functional immunity. The primary goals of this project are to i) develop a microfluidic platform to capture and
isolate B cells according to their binding avidity for viral antigens, and ii) use the platform to examine how B cell
binding avidity changes in time (affinity maturation) following infection and correlates with functional immunity.
Our long-term objective is to develop new tools with which to rapidly and effectively assess immune cell
function. This project expands on our previous work with tumor-specific T cells, and specifically examines the B
cell response to influenza A in hybridoma and murine model systems. The specific aims of this project are to:
1) Design and optimize a microfluidic device to determine the specificity and binding avidities of influenza virus
nuclear protein (NP)- and hemagglutinin (HA)-specific monoclonal B cells; and 2) characterize binding avidity
dynamics of HA- and NP-specific peripheral B cells following influenza virus infection. Our platform will
demonstrate the functionality of a rapid and easily adaptable system to evaluate the dynamics of the B cell
response to influenza but is completely adaptable to host of other pathogens such as SARS-Cov-2.
Furthermore, the project will begin to vigorously test long-held dogmas regarding the potential critical
importance of affinity maturation in the complex setting of an acute infection that induces polyclonal
extrafollicular and germinal center B cell responses, as well as local and systemic B cell immunity, where
related earlier studies have failed to demonstrate affinity maturation as a main driver of protective immunity.