PBMC (Peripheral Blood Mononuclear Cells) /Lymphocyte SPECT (Single Photon Emission Computerized Tomography) Imaging in Crohn's Disease

Using scintigraphic imaging including planar scintigraphy and SPECT, this study will evaluate the utility of two different ex vivo 99mTc-HMPAO labelled mononuclear cell populations in order to select the optimal methodology (using PBMC or purified lymphocyte subpopulations) for future drug intervention studies in Crohn's disease. Two parallel exploratory approaches will be investigated to enrich for lymphocyte populations expressing leukocyte trafficking inhibitors. In the first, whole blood will be fractionated on a ficoll gradient to purify a heterogeneous population of all the peripheral blood mononuclear cells (PBMC) for labelling. Secondly, further enrichment will be attempted using depletion of PBMC fractions of monocytes and B cells.