Multi-center determination of galectin-3 assay performance characteristics: Anatomy of a novel assay for use in heart failure.
BACKGROUND
Galectin-3 is a carbohydrate binding protein that plays many important regulatory roles in inflammation, immunity and cancer. Recent studies indicate that galectin-3 is a mediator of heart failure development and progression. Development of an improved assay for galectin-3 measurement was necessary for appropriate clinical assessment. Key analytical performance characteristics, the reference distribution and association of galectin-3 levels with clinical outcome in heart failure patients are defined.


METHODS
A two-site ELISA test was examined for measurement matrix, imprecision, limits of blank, detection, and quantitation, as well as linearity, high-dose hook effect, storage stability, cross-reactivity with nine similar compounds, interference with 22 common medications and icterus, lipemia and hemolysis, all in accordance with CLSI guidance. Also the effects of human anti-mouse antibodies and rheumatoid factor on recovery of galectin-3 were investigated. The reference interval was determined for 1092 ostensibly healthy individuals. The association of galectin-3 concentrations with an outcome of mortality was examined in a preliminary analysis of 129 acute decompensated heart failure patients.


RESULTS
Galectin-3 results were equivalent when measured in serum or EDTA plasma. Imprecision studies demonstrated that the total CV was <10% at a low concentration of 6 ng/mL, 7% near the mid-level concentration of 21 ng/mL, and 15% at the high level of 70 ng/mL. The limit of blank was 0.86 ng/mL, the limit of detection was 1.13 ng/mL, and the limit of quantitation was 0.96 ng/mL. The linear measurement range was 0.96-130 ng/mL and there was no high-dose hook at levels up to 500 ng/mL. No cross-reactivity with nine compounds structurally related to galectin-3 and no interference from 22 common medications, icterus or lipemia was found. Hemolysis and presence of human anti-mouse antibodies or rheumatoid factor were found to be potential sources of interference. Samples can be stored for up to 15 days at either 22-28 degrees C or 2-8 degrees C before analysis; measurements are stable after storage at -20 degrees C or -70 degrees C for at least 6 months and through six freeze-thaw cycles. The 90th, 95th and 97.5th percentile of the normal reference interval was 17.6, 20.3 and 22.1 ng/mL, respectively. Galectin-3 in the acute decompensated heart failure patients ranged from 4.0 to 75 ng/mL; using a cutpoint of 22.1 ng/mL in an unadjusted analysis, galectin-3 values were associated with an outcome of death (p=0.035). Galectin-3 is associated with severity of heart failure as indicated by NYHA Class (p-value for trend, 0.017).


CONCLUSIONS
This ELISA for galectin-3 measurement demonstrated acceptable analytical characteristics and was associated with mortality in a preliminary unadjusted analysis.
University of Maryland School of Medicine, Baltimore, MD, USA. RCHRISTENSON@umm.edu
Robert H
RH
Christenson
Show-Hong
SH
Duh
Alan H B
AH
Wu
Andrew
A
Smith
Gyorgy
G
Abel
Christopher R
CR
deFilippi
Shunguang
S
Wang
Aram
A
Adourian
Carol
C
Adiletto
Peter
P
Gardiner
D000368:Aged; D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D037502:Galectin 3 / Q000097:blood*; D006333:Heart Failure / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D057230:Limit of Detection; D008297:Male; D051379:Mice; D008875:Middle Aged
D037502:Galectin 3