The platelet neutralization test is used in the laboratorvy diagnosis of the lupus anticoagulant (Laffan and Manning, Dacie and Lewis practical haematology. Churchill Livingstone, Philadelphia, PA, pp 445-446, 2006). The lupus anticoagulant typically causes prolongation of phospholipid-dependent coagulation tests such as APTT, DRVVT, etc. The phospholipid-dependent nature of the LA can be demonstrated by adding washed and "fractured" platelets as a source of phospholipid and repeating the tests. If an LA is present in the sample, the addition of platelets will correct the prolonged clotting times. This appears to be due to the ability of the platelets to absorb the LA and negate its effect on the clotting time (Br J Haematol 109:704-715, 2001).