Limulus amebocyte lysate

Limulus amebocyte lysate (LAL) is an aqueous extract of blood cells (amebocytes) from the Atlantic horseshoe crab, Limulus polyphemus. LAL reacts with bacterial endotoxin lipopolysaccharide (LPS), which is a membrane component of gram-negative bacteria. This reaction is the basis of the LAL test, which is widely used for the detection and quantification of bacterial endotoxins.

History

The LAL test was developed by Frederik Bang and Jack Levin. Bang discovered that the blood of the horseshoe crab coagulates when exposed to bacterial endotoxins. Levin developed a method for using this reaction to detect and measure the amount of endotoxins present in a sample.

Procedure

The LAL test is performed by mixing a sample with the LAL. The mixture is then incubated, and the degree of clotting or turbidity is measured. The amount of endotoxin in the sample is directly proportional to the degree of reaction observed.

Applications

The LAL test is used in the pharmaceutical and medical device industries to test for endotoxins in products that will come into contact with the human body. It is also used in environmental monitoring and in research settings.

Advantages and Limitations

The LAL test is highly sensitive and specific for bacterial endotoxins. However, it can be affected by other substances in the sample that may interfere with the reaction. Therefore, it is important to validate the test for each type of sample to be tested.

See Also

• Endotoxin
• Gram-negative bacteria
• Lipopolysaccharide
• Horseshoe crab
• Frederik Bang
• Jack Levin