Saponin and other haemolysins (vitamin A, aliphatic amines, polyene antibiotics) as adjuvants for SRBC in the mouse. Evidence for a role for cholesterol-binding in saponin adjuvanticity.

The hypothesis that the adjuvant, as well as the haemolytic, activity of saponin depends on binding to cholesterol in cell membranes is supported by showing that cholesterol absorbs out adjuvant activity, and inhibits immunopotentiation in vivo when added to the injection mixture. Also, out of a range of haemolytic substances, chosen for their known properties as adjuvants or for cholesterol binding, the only materials which displayed a comparable activity to saponin were the polyene antibiotics Nystatin and Amphotericin B, whose binding to membrane cholesterol causes similar morphological changes to that of saponin.