99mTc-interleukin-2 scintigraphy in normal subjects and in patients with autoimmune thyroid diseases: a feasibility study.
OBJECTIVE
Radiolabelled interleukin-2 is a radiopharmaceutical used for the study of chronic inflammatory processes. (123)I-labelled interleukin-2 has successfully been used in a large number of patients affected by several immune-mediated diseases. (123)I, however, is expensive and not readily available. We have, therefore, developed a method for labelling interleukin-2 with (99m)Tc to high specific activity based on the use of an N(3)S bifunctional chelating agent. In this paper, we describe the results obtained with (99m)Tc-interleukin-2 in a series of eight normal subjects and of 12 patients with autoimmune thyroid diseases.


METHODS
Biodistribution, pharmacokinetics, haematological and systemic toxicity, radiation absorbed dose and in vivo targeting were studied.


RESULTS
Results showed rapid plasma clearance of (99m)Tc-interleukin-2 with retention mainly in the kidneys. Biodistribution and kinetics were similar to that observed for (123)I-interleukin-2. No acute systemic toxicity was found; a small decrease in peripheral blood lymphocytes was observed in the first hours only in patients, but it was mild and transient. (99m)Tc-interleukin-2 accumulated, to varying extents, in the thyroid of all patients affected by autoimmune thyroid diseases but not in the thyroid of normal subjects. The effective dose equivalent of a diagnostic activity of (99m)Tc-interleukin-2 (185 MBq) was 1.35 mSv. No correlation was observed between thyroid autoantibodies and uptake of (99m)Tc-interleukin-2.


CONCLUSIONS
The use of (99m)Tc-interleukin-2 is safe and simple; the favourable dosimetry and biodistribution and the rapid clearance make it potentially useful for the study of chronic inflammatory diseases such as autoimmune thyroid disease.
Chianelli
M
M
SSD di Medicina Nucleare, Dipartimento di Diagnostica, Ospedale Regina Apostolorum, Albano-Rome, Italy. marcochianelli@libero.it
Mather
S J
SJ
Grossman
A
A
Sobnak
R
R
Fritzberg
A
A
Britton
K E
KE
Signore
A
A
D000328:Adult; D001327:Autoimmune Diseases / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D005240:Feasibility Studies; D005260:Female; D006098:Granulocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000493:pharmacokinetics / Q000633:toxicity; D007700:Kinetics; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008657:Metabolic Clearance Rate; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics / Q000633:toxicity; D011829:Radiation Dosage; D011877:Radionuclide Imaging; D013959:Thyroid Diseases / Q000000981:diagnostic imaging*; D014018:Tissue Distribution
D007376:Interleukin-2; D015609:Organotechnetium Compounds; C481016:technetium Tc 99m interleukin 2