Phenotypic characterization of circulating antibody-secreting cells after mucosal and systemic immunizations in...

We have developed a simple approach for immunophenotyping of functional lymphoid cell subpopulations. Using this approach we have partly characterized circulating antigen-specific ASC after systemic versus mucosal immunization with respect to maturational and activation stages, and to their anatomic commitment(s). Comparative analyses of mucosally versus systemically activated circulating ASC reveal differences with respect not only to utilization of homing receptor molecules but also to certain activation markers, and especially cell surface MHC class II molecules. We have now extended these studies to several other markers including early and late B-cell maturation markers, and we are currently examining whether differential expression of HLA-DQ molecules on the majority of mucosally activated blood ASC may explain the relative inability of these cells to present soluble antigens to class II-restricted T-cells.