ABSTRACT
Research on the immunology of syphilis, and particularly research on antibodies that occur in the course of syphilis, has provided a vast and fascinating literature on antibodies to lipid antigens. Recognition of the important diagnostic usefulness of detecting antibodies to lipids in syphilis led very early to considerable interest in the immunology of two phospholipids—lecithin (phosphatidylcholine) and cardiolipin (diphosphatidylglycerol) and a steroid compound (cholesterol). Although murine myeloma antibodies to phosphocholine do not necessarily react with lecithin in liposomes, they can react with lecithin either in lipid emulsions, or in monomolecular films. The theory of haptens was derived at least in part from Landsteiner’s own immunological studies on lipids as antigens. Bromelin (or bromelain) is a protolytic enzyme that is commonly used as a clinical laboratory reagent to expose blood group substances (which are often glycolipids) on erythrocytes in order to amplify the serological activities of antibodies to the erythrocytes.
