Two binding sites for [3H]PBR28 in human brain: implications for TSPO PET imaging of neuroinflammation

David R Owen, Owain W Howell, Sac-Pham Tang, Lisa A Wells, Idriss Bennacef, Mats Bergstrom, Roger N Gunn, Eugenii A Rabiner, Martin R Wilkins, Richard Reynolds, Paul M Matthews, Christine A Parker

Research output: Contribution to journalArticlepeer-review

184 Citations (Scopus)


[(11)C]PBR28, a radioligand targeting the translocator protein (TSPO), does not produce a specific binding signal in approximately 14% of healthy volunteers. This phenomenon has not been reported for [(11)C]PK11195, another TSPO radioligand. We measured the specific binding signals with [(3)H]PK11195 and [(3)H]PBR28 in brain tissue from 22 donors. Overall, 23% of the samples did not generate a visually detectable specific autoradiographic signal with [(3)H]PBR28, although all samples showed [(3)H]PK11195 binding. There was a marked reduction in the affinity of [(3)H]PBR28 for TSPO in samples with no visible [(3)H]PBR28 autoradiographic signal (K(i)=188+/-15.6 nmol/L), relative to those showing normal signal (K(i)=3.4+/-0.5 nmol/L, P
Original languageEnglish
Pages (from-to)1608-1618
Number of pages11
JournalJournal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
Issue number9
Publication statusPublished - 2010


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