Analytic evaluation of a human ELISA kit for measurement of inhibin B in rat samples.
BACKGROUND
A cross-laboratory analytic evaluation of a commercially available human inhibin B ELISA for measuring inhibin B in rat serum and plasma has been undertaken.


METHODS
Dilution linearity, spiked recovery, intra- and inter-assay precision, functional sensitivity, matrix effects, and frozen stability were assessed across five laboratories. Reference ranges were generated for male Sprague Dawley and Han Wistar rats.


RESULTS
Acceptable performance was defined as an overall assay coefficient of variation ≤ 20% with an intraday LLOQ ≤ 20 pg/ml. Intra- and inter-assay precision and functional sensitivity (≤6.4 pg/ml) generally met these criteria, but with occasional evidence of greater variability, particularly at lower concentrations. Dilution linearity was acceptable with occasional low recovery. Acceptable recovery of kit calibrators from rat serum confirmed the absence of matrix effects. Matched serum and plasma samples gave comparable results. The signal increased on freezing, remained constant for ≥3 freeze-thaw cycles and was generally stable for at least 8 weeks. Mean inhibin B ranged from 33.5 to 140.6 pg/ml in adult rats across laboratories, with some evidence for a decline from 6 to 9 weeks of age. Power calculations using preliminary reference range data indicated 10 animals/group would generally detect a 40% decrease in inhibin B at AstraZeneca, but laboratories with lower control values would require larger groups.


CONCLUSIONS
The assay meets the analytical performance criteria; however, precision at the low end of the standard curve, biological variability, and low control values observed in some laboratories indicate that the utility of the assay may be limited in some laboratories.
AstraZeneca Research & Development, Global Safety Assessment, Alderley Park, Macclesfield, United Kingdom. michelle.coulson@astrazeneca.com
Michelle
M
Coulson
Sue
S
Bickerton
Catherine J
CJ
Betts
Matt
M
Jacobsen
Jane
J
Stewart
Robert E
RE
Chapin
William J
WJ
Reagan
James
J
Alvey
Zoltan
Z
Erdos
Louise Parks
LP
Saldutti
Manisha
M
Sonee
Nancy
N
Bogdan
Monica
M
Singer
Petra
P
Vinken
Valerie
V
Barlow
Karen
K
Czajkowski
James H
JH
Kim
D000818:Animals; D001681:Biological Assay; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005615:Freezing; D006801:Humans; D007265:Inhibins / Q000097:blood*; D008297:Male; D011786:Quality Control; D051381:Rats; D017207:Rats, Sprague-Dawley; D012015:Reference Standards; D012016:Reference Values; D044967:Serum / Q000378:metabolism
C422364:inhibin B; D007265:Inhibins