Fig. 1.

TSPO is expressed mainly on CD14+ monocytes and does not significantly vary over time within a donor. a TSPO expression of PBMC subsets is determined by Taqman, normalized to housekeeping gene HPRT, and expression relative to SupT1 cell line TSPO expression is graphed. Average relative expression from a representative experiment run in triplicate is shown. Total PBMC show a relative expression of 22, CD4+ and CD8+ populations show relative expression of approximately 7, CD14+ cells show a relative expression of 38. b TSPO expression as determined by a radioligand binding assay using [³H]PBR28, Bmax is plotted as the pmol of specific binding normalized to protein concentration. Mean Bmax of total PBMC from 3 HD is 0.69±0.28 pmol/mg, while mean Bmax of CD14+ cells from those HD is 1.17±0.54 pmol/mg. c [³H]PBR28 radioligand binding assays are used to determine the variability of peripheral TSPO expression over time. Bmax is plotted as the pmol of specific binding normalized to protein concentration. One HD has a Bmax of 1.05 pmol/mg at month 1, 1.1 pmol/mg at month 23, and 1.17 pmol/mg at month 27; the second HD has a Bmax of 0.8 pmol/mg at month 1, 0.7 pmol/mg at month 4, 0.72 pmol/mg at month 23, and 0.7 pmol/mg at month 27. No significant difference is found over time in these two donors