In Vivo Cytometry of Antigen-Specific T Cells Using F-19 MRI

Noninvasive methods to image the trafficking of phenotypically defined immune cells are paramount as we attempt to understand adaptive immunity. A F-19 MRI-based methodology for tracking and quantifying cells of a defined phenotype is presented. These methods were applied to a murine inflammation model using antigen-specific T cells. The T cells that were intracellularly labeled ex vivo with a perfluoropolyether (PFPE) nanoemulsion and cells were transferred to a host receiving a localized inoculation of antigen. Longitudinal F-19 MRI over 21 days revealed a dynamic accumulation and clearance of T cells in the lymph node (LN) draining the antigen. The apparent T-cell numbers were calculated in the LN from the time-lapse F-19 MRI data. The effect of in vivo T-cell division on the F-19 MRI cell quantification accuracy was investigated using fluorescence assays. Overall, in vivo cytometry using PFPE labeling and F-19 MRI is broadly applicable to studies of whole-body cell biodistribution. Magn Reson Med 62:747-753, 2009. (C) 2009 Wiley-Liss, Inc.