Ligands for Viscum album agglutinin and galectin-1 in human lung cancer: Is there any prognostic relevance?

Viscum album agglutinin (VAA) is an extract component of mistletoe. It belo ngs to the plant lectin family and exerts various biological effects such a s cytotoxic properties for tumor cells in culture. VAA as well as galectin- 1, an endogenous lectin, possess galactose-specific surface-binding sites. We therefore investigated 159 cases of lung cancer for their capacity to bi nd VAA and galectin-1 and for Lewis antigen reactivity. Three different met hods were used for detection of VAA: a two-step method with biotinylated VA A; an immune complex three-step method, and a four-step method. The most se nsitive results were obtained with the four-step method utilising VAA, a go at-anti-VAA antibody and a biotinylated rabbit-anti-goat antibody. Intensit y and distribution of staining were assessed using an immunoreactive score index (0-12). Approximately 70% of all tumors exhibited moderate to strong binding capacity for VAA. Adenocarcinomas and bronchiolo-alveolar carcinoma s were more frequently labeled than squamous carcinomas. No relationship be tween expression of binding sites for VAA and galectin-1 as well as of Lewi s antigens was found. Moreover, there was no correlation between VAA-bindin g capacity and survival, whereas expression of galectin-1-binding sites was of prognostic significance. Patients showing expression of galectin-1-bind ing sites revealed a better prognosis than those lacking binding sites or s howing a weak reactivity (P = 0.0257 log rank test of Kaplan-Meier statisti cs).