Microparticle-enhanced nephelometric immunoassay of lysozyme in milk and other human body fluids

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Quantitation of lysozyme in human milk was performed by a microparticle-enhanced nephelometric immunoassay based on the measurement of the light scattered during the competitive immunoagglutination of a microparticle–lysozyme conjugate with an anti-lysozyme antiserum. This immunoassay has a detection limit of 8 µg/L of reaction mixture and can be performed using diluted milk (1:6000, in reaction mixture), excluding sample pretreatment. Human milk lysozyme can be quantified over the concentration range 0.09–1.50 g/L, with within- and between-run coefficients of variation <5%. Changes in the lysozyme concentration of human milk during lactation were determined in 636 samples. Lysozyme concentrations (mean ± SE) decreased from colostrum (0.36 ± 0.02 g/L) to transitional milk (0.30 ± 0.01 g/L) and mature milk during days 15–42 (0.30 ± 0.01 g/L), then increased in the mature milk during days 43–56 (0.35 ± 0.01 g/L) and especially during days 57–84 (0.83 ± 0.05 g/L). The proportion of lysozyme contributing to total protein was found to rise during lactation and was as follows: colostrum (1.7%), transitional milk (2.3%), and mature milk from days 15–28 (2.7%), days 29–42 (3.1%), days 43–56 (3.8%), and days 57–84 (7.3%). The assay developed for milk was also suitable for the determination of lysozyme in other human body fluids.

The following articles in journals at HighWire Press have cited this article:

				B. W. A. van der Strate, M. C. Harmsen, P. Schafer, P. J. Swart, T. H. The, G. Jahn, C. P. Speer, D. K. F. Meijer, and K. Hamprecht Viral Load in Breast Milk Correlates with Transmission of Human Cytomegalovirus to Preterm Neonates, but Lactoferrin Concentrations Do Not Clin. Vaccine Immunol., July 1, 2001; 8(4): 818 - 821. [Abstract] [Full Text] [PDF]