123I-interleukin-2 scintigraphy for in vivo assessment of intestinal mononuclear cell infiltration in Crohn's disease.
Activated mononuclear cells expressing interleukin-2 (IL2) receptors (IL2-Rs) heavily infiltrate the Crohn's disease (CD) gut wall. A new technique for the in vivo detection of tissue infiltrating IL2-R positive (IL2R+ve) cells was developed based on 123I-IL2 scintigraphy. The aim of this study was to investigate whether 123I-IL2 accumulates in the CD gut wall in different phases of the disease and to evaluate the specificity of 123I-IL2 binding to activated IL2R+ve cells infiltrating the gut wall.


METHODS
Fifteen patients with ileal CD (10 active and 5 inactive) and 10 healthy volunteers were studied by 123I-IL2 scintigraphy. Six patients with active CD were studied before and after 12 wk of steroid treatment. After scintigraphy, patients were followed up for 29-54 mo. Ex vivo autoradiography was performed to determine specificity of 125I-IL2 binding to IL2R+ve cells. For bowel scintigraphy, 123I-IL2 (75 MBq) was injected intravenously and gamma camera images were acquired after 1 h. Bowel radioactivity was quantified in 64 regions of interest (ROIs).


RESULTS
Autoradiography showed specific binding of 125I-IL2 to IL2R+ve mononuclear cells infiltrating the CD gut wall. Intestinal 123I-IL2 uptake assessed by the number of positive ROIs was higher in patients with active or inactive CD than in healthy volunteers (P < 0.0001 and P = 0.03, respectively) and positively correlated with the CD activity index (P = 0.01). 123I-IL2 intestinal uptake significantly decreased in patients with CD in steroid-induced remission (P = 0.03). A significant correlation was observed between the number of positive ROIs and time to disease relapse.


CONCLUSIONS
123I-IL2 accumulates in the diseased CD gut wall by specific binding to IL2R+ve cells, infiltrating the involved tissues. 123I-IL2 scintigraphy may be an objective tool for the in vivo assessment of intestinal activated mononuclear cell infiltration.
Signore
A
A
Department of Clinical Sciences, University La Sapienza, Rome, Italy.
Chianelli
M
M
Annovazzi
A
A
Bonanno
E
E
Spagnoli
L G
LG
Pozzilli
P
P
Pallone
F
F
Biancone
L
L
D000328:Adult; D001345:Autoradiography; D016022:Case-Control Studies; D003424:Crohn Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007082:Ileum / Q000000981:diagnostic imaging; D007376:Interleukin-2 / Q000493:pharmacokinetics; D007457:Iodine Radioisotopes; D008297:Male; D011877:Radionuclide Imaging; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D012680:Sensitivity and Specificity
D007376:Interleukin-2; D007457:Iodine Radioisotopes; D015375:Receptors, Interleukin-2