title: A new method for the measurement of lysosomal acid lipase in dried blood spots using the inhibitor Lalistat 2.
abstract: BACKGROUND
  Cholesterol ester storage disease (CESD) and Wolman Disease (WD) are due to deficiency of lysosomal acid lipase (LAL). A new method is described for the measurement of LAL in dried blood spots (DBS) using Lalistat 2 an inhibitor of LAL.
  
  
  METHODS
  LAL activity in DBS extracts was measured using the substrate 4-methylumbelliferyl palmitate. LAL activity was determined by measuring total lipase activity and lipase activity in the presence of Lalistat 2. The specificity of Lalistat 2 was investigated using human recombinant LAL (hrLAL) and human pancreatic lipase (hPL).
  
  
  RESULTS
  Lalistat 2 inhibited hrLAL with 1% residual activity at 1 μM inhibitor but had no effect on hPL up to 10 μM. LAL activity in DBS samples obtained from normal controls (n=140) was 0.50-2.30 nmol/punch/h and in patients with CESD was <0.03 nmol/punch/h (n=11). Activity in carriers showed intermediate activity: 0.15-0.40 nmol/punch/h (n=15).
  
  
  CONCLUSIONS
  Measurement of LAL using DBS is made difficult by the presence of other lipases in whole blood. Lalistat 2 is a specific inhibitor of LAL which allows the determination of LAL in DBS. Results show the method differentiates clearly between normal controls, carriers and affected cases.
authors.affiliation: Biochemistry Department, Yorkhill Hospital, Yorkhill, Glasgow, United Kingdom. john.hamilton2@ggc.scot.nhs.uk
authors.forename: John
authors.initials: J
authors.lastname: Hamilton
authors.forename: Iain
authors.initials: I
authors.lastname: Jones
authors.forename: Rajeev
authors.initials: R
authors.lastname: Srivastava
authors.forename: Peter
authors.initials: P
authors.lastname: Galloway
mesh_terms: D002219:Carbamates / Q000494:pharmacology*; D019963:Clinical Chemistry Tests / Q000379:methods*; D059788:Dried Blood Spot Testing / Q000379:methods*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004795:Enzyme Stability; D006801:Humans; D008049:Lipase / Q000037:antagonists & inhibitors / Q000097:blood; D002787:Sterol Esterase / Q000037:antagonists & inhibitors / Q000097:blood*; D013696:Temperature; D013830:Thiadiazoles / Q000494:pharmacology*
chemical_list: D002219:Carbamates; D004791:Enzyme Inhibitors; D013830:Thiadiazoles; C576036:lalistat 2; C503451:LIPA protein, human; D002787:Sterol Esterase; D008049:Lipase; C518354:PNLIP protein, human