Radioiodinated peanut lectin: clinical use as a tumour-imaging agent and potential use in assessing renal-tubular function.

Peanut lectin (PNA) has been shown to have a high affinity for Thomsen-Friedenreich (T) antigen, which is associated with the membrane of many solid tumour cells. PNA labelled with 131I was used as a tumour-imaging substance in patients with known metastatic cancer. Serial gamma scintiscans were obtained in 17 patients following a single injection of 131I-labelled PNA. Only in 1 patient was this technique able to reveal a known metastasis at analogue imaging. In the remaining patients, no visible uptake of 131I-PNA could be demonstrated at sites of known metastases. PNA is rapidly excreted through the kidneys and localizes in the renal tubules. As a tumour-imaging agent, 131I-PNA appears to be without value, but its renal-excretory characteristics make it a potentially useful agent for the in vivo assessment of renal-tubular disorders.