Clinical significance of plasma apolipoprotein F in Japanese healthy and hypertriglyceridemic subjects.
OBJECTIVE
Apolipoprotein F (apo F), also known as lipid transfer inhibitory protein (LTIP), is a protein component of plasma lipoprotein classes including HDL and functions to inhibit lipid transfer between lipoproteins in vitro. To study the role of plasma apo F, a reliable and sensitive tool for the quantification would be needed.


METHODS
We have developed a sandwich ELISA using two monoclonal antibodies for human plasma apo F, and analyzed apo F concentration in 397 Japanese healthy and 221 hypertriglyceridemic subjects.


RESULTS
Our ELISA enables apo F to be assayed in the range of 0.6-25 µg/mL with intra- and inter-assay coefficients of variation less than 3.8% and 7.8%, respectively. In healthy subjects, plasma apo F concentration was 12.5±2.9 µg/mL (mean±SD), and was significantly higher in females than in males (p<0.05). By linear regression analysis in healthy subjects, plasma apo F concentration correlated positively with HDL cholesterol and apo A-I levels, and in males but not in females, negatively with apo B and triglyceride levels. It also correlated negatively with intrinsic CETP activity measured using intrinsic apo B-containing lipoprotein as an acceptor, and positively with PLTP mass and apo J levels. Apo F concentration in hypertriglyceridemic patients (10.3±3.1 µg/mL) was lower than in healthy controls (p<0.0001) and correlated positively with PLTP mass.


CONCLUSIONS
Our ELISA is reliable and sensitive for the quantification of plasma apo F concentration. This system can be applicable for clinical significance in lipoprotein metabolism and reverse cholesterol transport.
Advanced Medical Technology and Development Division, BML, Inc., Saitama, Japan.
Takeshi
T
Kujiraoka
Takaaki
T
Nakamoto
Hiroyuki
H
Sugimura
Tadao
T
Iwasaki
Mitsuaki
M
Ishihara
Toshiyasu
T
Hoshi
Yasuto
Y
Horie
Kazuyuki
K
Ogawa
Masakatsu
M
Todoroki
Yuki
Y
Nakatani
Nobuyuki
N
Banba
Takanori
T
Yasu
Hiroaki
H
Hattori
D000328:Adult; D016632:Apolipoprotein A-I / Q000097:blood; D001053:Apolipoproteins / Q000097:blood*; D001055:Apolipoproteins B / Q000097:blood; D044466:Asian People; D053480:Cholesterol Ester Transfer Proteins / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D019976:Cloning, Organism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015228:Hypertriglyceridemia / Q000097:blood*; D007564:Japan; D008297:Male; D049294:Phospholipid Transfer Proteins / Q000097:blood; D011994:Recombinant Proteins; D012737:Sex Factors; D014280:Triglycerides / Q000097:blood
D016632:Apolipoprotein A-I; D001053:Apolipoproteins; D001055:Apolipoproteins B; C506642:CETP protein, human; D053480:Cholesterol Ester Transfer Proteins; D008076:Cholesterol, HDL; C493430:PLTP protein, human; D049294:Phospholipid Transfer Proteins; D011994:Recombinant Proteins; D014280:Triglycerides; C036321:apolipoprotein F