Validation of an autotaxin enzyme immunoassay in human serum samples and its application to hypoalbuminemia differentiation.
BACKGROUND
Autotaxin (ATX), a tumor cell motility-stimulating factor, regulates the blood concentrations of lysophosphatidic acid (LPA), an important and multi-functional bioactive lipid, through its lysophospholipase D activity (lysoPLD). The introduction of ATX measurements into clinical laboratory testing is urgently needed.


METHODS
Anti-human ATX monoclonal antibodies were produced by immunization of recombinant human ATX expressed in a baculovirus system. An immunoassay for the quantitative determination of ATX was established, and human serum samples were assayed.


RESULTS
The within-run and between-run precision, interference, detection limit, and linearity studies were satisfactory. The central 95 percentile reference interval for the serum ATX antigen concentration in healthy subjects was 0.468-1.134 mg/l (n=120) and was strongly correlated with the serum lysoPLD activity. The ATX concentration was significantly (p<0.001) higher in women (0.625-1.323 mg/l) than in men (0.438-0.914 mg/l). The serum ATX concentrations were increased in patients with chronic liver diseases and decreased in postoperative prostate cancer patients but were not altered in nephrosis patients. Thus, serum ATX antigen concentrations could be used to discriminate these hypoalbuminemia conditions.


CONCLUSIONS
The present ATX antigen assay may be useful for clinical laboratory testing.
Nakamura
Kazuhiro
K
Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan.
Igarashi
Koji
K
Ide
Kazufumi
K
Ohkawa
Ryunosuke
R
Okubo
Shigeo
S
Yokota
Hiromitsu
H
Masuda
Akiko
A
Oshima
Noriko
N
Takeuchi
Takumi
T
Nangaku
Masaomi
M
Okudaira
Shinichi
S
Arai
Hiroyuki
H
Ikeda
Hitoshi
H
Aoki
Junken
J
Yatomi
Yutaka
Y
D000941:Antigens / Q000097:blood; D002908:Chronic Disease; D005260:Female; D006262:Health; D006801:Humans; D034141:Hypoalbuminemia / Q000097:blood* / Q000175:diagnosis*; D007124:Immunoenzyme Techniques / Q000379:methods*; D008107:Liver Diseases / Q000378:metabolism; D008297:Male; D009097:Multienzyme Complexes / Q000097:blood* / Q000235:genetics / Q000302:isolation & purification; D009401:Nephrosis / Q000097:blood; D043264:Phosphodiesterase I / Q000097:blood* / Q000235:genetics / Q000302:isolation & purification; D010739:Phospholipase D / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases; D011471:Prostatic Neoplasms / Q000097:blood / Q000601:surgery; D011755:Pyrophosphatases / Q000097:blood* / Q000235:genetics / Q000302:isolation & purification; D000099189:Lysophospholipase D
D000941:Antigens; D009097:Multienzyme Complexes; D043264:Phosphodiesterase I; D010739:Phospholipase D; D010727:Phosphoric Diester Hydrolases; D011755:Pyrophosphatases; D000099189:Lysophospholipase D