Streptolysin O, a cholesterol-binding toxin from Streptococcus pyogenes, is widely used in research to study cell membrane permeability and pore formation. It is particularly valuable in experiments involving the lysis of red blood cells to investigate hemolytic activity. This toxin is also employed in immunology to understand host-pathogen interactions and immune responses, as it induces specific antibody production. Additionally, Streptolysin O is utilized in creating permeabilized cell models to study intracellular processes and drug delivery mechanisms. Its ability to bind cholesterol in cell membranes makes it a useful tool for membrane biology studies. Furthermore, it is applied in clinical diagnostics through anti-streptolysin O (ASO) titer tests to detect antibodies in blood, aiding in the diagnosis of post-streptococcal complications such as rheumatic fever and glomerulonephritis.