Antigen-specific humoral immune responses in vitro

Abstract

Introduction: FNAIT is a condition were the immune system of a pregnant woman is activated and produces antibodies against an unborn child’s blood platelets. The mechanisms behind the activation of the B-cells remain unknown. The purpose of this research was to look at antigen-specific humoral immune responses associated with FNAIT. Our goal was to activate antigen-specific B-cells in vitro. Method: In order to establish a cell culture system to study activation of memory B-cells in vitro, PBMC from three donors were cultured with cytokines, antigen and EL-4-B5. B-cells were sorted with MACS, and flow cytometry was performed to analyse cell populations and to identify and isolate antibody-secreting plasmablasts. B-cell activation was confirmed by antibody production measured with ELISA, and/or detection of plasmablasts with ELISpot. Results: Cultures showed increased number of plasmablasts producing IgG antibodies. EL-4-B5 was most important to activate and stimulate B-cells, and antigen had a synergic effect. Only a limited number of antigen-specific plasmablasts and antibodies were detected. Conclusion: Isolated B-cells in culture with antigen, cytokines and CD40L+ EL-4-B5 cells, differentiated to plasmablasts producing IgG, which were successfully identified with flow cytometry. Further research is needed to develop a method to activate antigen-specific B-cells.