1% of saponin solution can hemolyze erythrocytes. Saponin solutions have been used in the following ways: concentrations of 0.005%-0.01% were used to permeabilize cultured human intestinal epithelial cells after incubation for 30' prior to immunofluorescence; a 0.05% solution of saponin was reportedly used to permeabilize paraformaldehyde-saponin- fixed human fibroblasts for the staining of intracellular fibronectin by different types of peroxidase conjugates for light and electron microscopy; saponins, a surface-active agent, have also been used to lyse the outer membranes of Rous sarcoma viruses, cell membranes of chicken liver and erythrocytes of human and guinea pig. It also has been used as an adjuvant for vaccines. MW 1000-2000 I (8047-15-2]