Good agreement between capillary and venous sampling for lectin pathway proteins.

Background: The lectin pathway of complement activation, in particular mannose-binding lectin (MBL), has been extensively investigated over recent years. So far, studies were exclusively based on venous samples. The aim of this study was to investigate whether measurements of lectin pathway proteins obtained by capillary sampling are in agreement with venous samples.
Methods: Prospective study including 31 infants that were admitted with suspected early-onset sepsis. Lectin pathway proteins were measured in simultaneously obtained capillary and venous samples. Bland-Altman plots of logarithmized results were constructed, and the mean capillary to venous ratios (ratiocap/ven) were calculated with their 95% confidence intervals (CI).
Results: The agreement between capillary and venous sampling was very high for MBL (meanratiocap/ven, 1.01; 95% CI, 0.85-1.19). Similarly, high agreement was observed for H-ficolin (meanratiocap/ven, 1.02; 95% CI, 0.72-1.44), MASP-2 (1.04; 0.59-1.84), MASP-3 (0.96; 0.71-1.28), and MAp44 (1.01; 0.82-1.25), while the agreement was moderate for M-ficolin (meanratiocap/ven, 0.78; 95% CI, 0.27-2.28).
Conclusions: The results of this study show an excellent agreement between capillary and venous samples for most lectin pathway proteins. Except for M-ficolin, small volume capillary samples can thus be used when assessing lectin pathway proteins in neonates and young children.
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