Imperial College London

Professor Paul M. Matthews

Faculty of MedicineDepartment of Brain Sciences

Edmond and Lily Safra Chair. Head of Department



+44 (0)20 7594 2855p.matthews




Ms Siobhan Dillon +44 (0)20 7594 2855




E502Burlington DanesHammersmith Campus






BibTex format

author = {Owen, DR and Howell, OW and Tang, SP and Wells, LA and Bennacef, I and Bergstrom, M and Gunn, RN and Rabiner, EA and Wilkins, MR and Reynolds, R and Matthews, PM and Parker, CA},
doi = {10.1038/jcbfm.2010.63},
journal = {J Cereb Blood Flow Metab},
pages = {1608--1618},
title = {Two binding sites for [3H]PBR28 in human brain: implications for TSPO PET imaging of neuroinflammation},
url = {},
volume = {30},
year = {2010}

RIS format (EndNote, RefMan)

AB - [(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<0.001). Of this latter group, [(3)H]PBR28 bound with a two-site fit in 40% of cases, with affinities (K(i)) of 4.0+/-2.4 nmol/L (high-affinity site) and 313+/-77 nmol/L (low-affinity site). There was no difference in K(d) or B(max) for [(3)H]PK11195 in samples showing no [(3)H]PBR28 autoradiographic signal relative to those showing normal [(3)H]PBR28 autoradiographic signal. [(3)H]PK11195 bound with a single site for all samples. The existence of three different binding patterns with PBR28 (high-affinity binding (46%), low-affinity binding (23%), and two-site binding (31%)) suggests that a reduction in [(11)C]PBR28 binding may not be interpreted simply as a reduction in TSPO density. The functional significance of differences in binding characteristics warrants further investigation.
AU - Owen,DR
AU - Howell,OW
AU - Tang,SP
AU - Wells,LA
AU - Bennacef,I
AU - Bergstrom,M
AU - Gunn,RN
AU - Rabiner,EA
AU - Wilkins,MR
AU - Reynolds,R
AU - Matthews,PM
AU - Parker,CA
DO - 10.1038/jcbfm.2010.63
EP - 1618
PY - 2010///
SN - 1559-7016
SP - 1608
TI - Two binding sites for [3H]PBR28 in human brain: implications for TSPO PET imaging of neuroinflammation
T2 - J Cereb Blood Flow Metab
UR -
UR -
VL - 30
ER -