Immunity & infection
A new high dimensional single cell mass cytometry approach called ’CyTOF’, for Cytometry by Time-of-Flight, permits the simultaneous detection of ~ 40 phenotypic and functional immune markers in individual cells without the issues of spectral overlap seen in traditional flow cytometry. In this study we applied CyTOF to comprehensively characterize the circulating immune cell populations in elderly individuals both before and after administration of an exploratory adjuvanted protein vaccine in a Phase 1a trial. As previously reported, the vaccine cohort receiving the highest dose of soluble respiratory syncytial virus (RSV) fusion (F) glycoprotein in a TLR4 agonist adjuvant emulsion formulation demonstrated antigen-specific cellular responses by IFNg ELISPOT. However, the CD4/CD8 contribution of the response was not determined and it was unclear why some subjects did not mount a detectable T cell ELISPOT response. Our approach was to use CyTOF to further interrogate the T cell response in this vaccine dose cohort. Participants showed both CD4 and CD8 IFNg responses following stimulation of patient PBMC with RSV(F) peptides. Several statistical techniques are being employed to analyze the differences between responders and non-responders. Using viSNE analysis, we found increased expression of CD4 and CD8 HLA-DR, CCR7, CD127 and CD69 in non-responders versus responders. Citrus analysis is currently underway to further explore differences between responders and non-responders. High parameter CyTOF can help profile immune components associated with differential vaccine responsiveness.
Microbiology and Immunology Dept. Stanford University