The aim of this study was to evaluate accumulation of the low molecular peptides and proteins labelled with 99mTc in rat inflammatory/infection foci. Peptides (human leukocyte dialysate – HLD, thymosin fraction 5 – TF5, aprotinin – APT), proteins (human IgG – HIG) were labelled with 99mTc using a redox polymer. The labelling efficiency was evaluated using paper, TLC and/or column chromatography and electrophoresis. The biodistribution of the labelled substances was evaluated in Wistar rats with Staphylococcus aureus infection or with sterile kaolin suspension-induced inflammation in the left inguinal region 24 h after abscess induction.Accumulation of 99mTc activity was determined both by external gamma camera imaging and by counting dissected tissues 1–4 hours after administration. The evaluated peptides and proteins show a high labelling efficiency (99mTc-HLD>98 %, 99mTc-TF5>95 %, 99mTc-APT>98 %, 99mTc-HIG>95 %). Use of redox polymer for labelling raises the stability of 99mTc-labelled substances so that the labelling efficiency remains to be virtually the same (95–98 %) after 8 hours at least. In experimentally induced inflammation, the amount of 99mTc-peptides and 99mTc-HIG activity accumulated is 2.5–6.5 and 5.3–10.6 times, respectively, that in control tissue.A comparison of two types of model inflammations (inflammation induced by kaolin and Staphylococcus-induced inflammation) revealed the values measured with 99mTc-peptides are more than a double that induced by kaolin suspension. The studied low molecular peptides labelled with 99mTc allowrapid localisation of infection foci in the animalmodel. 99mTc labelled HIG seems to be useful for the detection of both infections and inflammatory lesions.

        Key words: technetium (99mTc) – inflammation – biodistribution – peptides – proteins