Methods: Mass cytometry was used to capture fluctuations in discrete B-cell populations during an experimental RV-16 infection in allergic asthmatics. The findings were used to inform the design of an antigen-specific fluorescence-based flow cytometry panel in order to further interrogate the B-cell compartment in relation to RV infection.
Results: B-cell antigen-specificity was validated in blood from control subjects and atopics using fluorescent tetramers of tetanus toxoid and Der p 1, respectively. We readily identified naïve B-cells (IgD+), plasmablasts (CD20-, CD38+), and 2 discrete memory populations that differentially expressed the follicular-homing marker, CXCR5. Whereas CXCR5+ memory cells expressed CD27 and diverse isotypes, their CXCR5- counterparts were CD27lo, expressed the transcription factor T-bet, and lacked IgM. This latter phenotype disappeared from the blood in conjunction with memory T-cells during the acute phase of RV infection, while plasmablasts that primarily expressed IgA were expanded.
Conclusions: Our findings are consistent with the presence of pre-existing memory B-cells that are poised for reactivation by cognate antigen stimulation, potentially with or without T-cell help. Further work is necessary to determine the B-cell mechanisms that promote virus-neutralizing activity, including how T-cells might instruct the protectiveness of antibodies produced.