Critical evaluation of a specific ELISA and two enzymatic assays of pancreatic lipases in human sera.
OBJECTIVE
Human pancreatic lipases (HPL) include the classical HPL, and two related proteins known as pancreatic lipase-related proteins 1 and 2 (HPLRP1 and 2). The aim of this study was to develop an ELISA for specifically quantifying the classical-HPL level in sera of patients with and without pancreatic disorders.


METHODS
The specific activity of various human (including classical-HPL) and microbial lipases was measured using Lipa Vitros and potentiometric (pH-stat) assays. A double sandwich ELISA was also set up, using an anti-classical-HPL polyclonal antibody and a biotinylated monoclonal antibody (mAb 146-40) specific to the classical-HPL. Sera (n = 53) were collected from patients with and without pancreatic disorders. The lipase concentration was deduced from the measured lipolytic activity and compared with the corresponding classical-HPL concentration, measured with the ELISA.


RESULTS
Both the purified HPLRP2 and 3 lipases of microbial origin were found to have a significant and unexpected lipolytic activity under the standard Lipa Vitros assay, whereas the ELISA test developed in the present study was found to be specific for the classical-HPL, due to the absence of cross-reactivity between mAb 146-40, HPLRP1 and HPLRP2. The efficiency of the ELISA was assessed in terms of its reproducibility and accuracy. The lower detection limit of classical-HPL was found to be 0.03 microg/l. A good correlation was found to exist between the lipase concentrations obtained in the ELISA, pH-stat and Lipa Vitros tests, in both the control and pathological groups.


CONCLUSIONS
This is the first time a specific method of measuring classical-HPL in human serum has been proposed. Using this ELISA, we established with the 53 sera selected in the present study, that the Lipa Vitros assay as well as the pH-stat assay were mostly detecting classical pancreatic lipase. However, it is possible that other lipases such as HPLRP2 or lipases of microbial origin, present in some pathological sera, may well interfere with the Lipa Vitros assay.
Laboratoire d'Enzymologie Interfaciale et de Physiologie de la Lipolyse du CNRS, UPR 9025, Marseille, France. grandval@ibsm.cnrs-mrs.fr
Philippe
P
Grandval
Alain
A
De Caro
Josiane
J
De Caro
Barbara
B
Sias
Frédéric
F
Carrière
Robert
R
Verger
René
R
Laugier
D000208:Acute Disease; D015415:Biomarkers / Q000097:blood; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D008049:Lipase / Q000097:blood*; D010195:Pancreatitis / Q000097:blood* / Q000201:enzymology*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D015415:Biomarkers; D008049:Lipase