Limulusamöbalysatstest

Limulusamöbalysatstest, commonly referred to as the LAL test, is an endotoxin assay used to detect lipopolysaccharide contamination in pharmaceuticals, medical devices, and injectable products. The assay derives its signal from amebocytes derived from the blood of horseshoe crabs of the genus Limulus, traditionally Limulus polyphemus in North America and related species elsewhere. Endotoxins from Gram-negative bacteria trigger a rapid reaction in the amebocytes, enabling sensitive detection of contamination.

The test is based on the coagulation cascade of the limulus amebocyte lysate. In the presence of endotoxin, the lysate coagulates to form a gel. Modern variants include gel-clot (end-point), turbidimetric (cloudiness increases with endotoxin concentration), and chromogenic (color change) formats.

It is widely used to ensure sterility of parenteral drugs, vaccines, intravenous solutions, implants, dialysis fluids, and medical devices. The method is specified in pharmacopeias such as the United States Pharmacopeia (USP) and the European Pharmacopoeia (EP) as a standard endotoxin assay for certain products.

Because the test traditionally uses horseshoe crab blood, harvesting can impact crab populations. To reduce animal use and ecological effects, recombinant Factor C (rFC) assays and other synthetic alternatives have been developed and are increasingly accepted in regulatory contexts where validated.

Limitations include susceptibility to interference from sample matrices and the potential for false positives or negatives if samples contain inhibitors or enhancers. Proper sample preparation and controls are essential for reliable results.