Potential applications of radionuclide-labelled liposomes in the detection of the lymphatic spread of cancer

The regional lymph node localisation of technetium-99 m labelled liposomes in Rd/3 tumour-bearing rats, following interstitial injection, was studied by external γ-camera imaging and tissue radioassay. Normal and control animals with either irradiated non-metastasising Rd/3 tumour cells or inflammation induced by Freund's adjuvant were also studied. The results showed that 99 m Tc-labelled neutral liposomes exhibited a marked inhibition of uptake by lymph nodes partially replaced by Rd/3 metastatic tumour, an enhanced uptake was observed in the presence of non-metastasising tumour cells in the regional field when compared to normal. In contrast 99 m Tc-labelled cationic liposomes showed a less marked suppression of uptake by lymph nodes containing metastases. These findings suggest that radiolabelled liposomes may be of value as a diagnostic test in the detection of the lymphatic spread of cancer as well as acting as an in vivo test of immunological function in regional lymph nodes. The uptake of cationic liposomes by lymph nodes bearing metastases suggest the targetting of this agent as a therapeutic carrier to diseased lymph nodes.