Antibodies against oxidized LDL in infants.

To the Editor: We conducted two studies of serum antibodies against oxidized LDL (IgoxLDL) in mothers and their infants during the past 2 years. We used an ELISA (oLAb; Eli-Tec Labor-reagenzien GmbH) based on the use of Cu 2ϩ-oxidized LDL particles bound to the surface of microtiter plate wells and an anti-human IgG-peroxidase conjugate. In the first study of mothers and their infants at birth and again at the age of 3 months (1), we found that the values were not homogeneous in the sera of 3-month-old infants: some infants had markedly increased IgoxLDL, whereas others had values below those in newborns. The mean value was 815 Ϯ 469 units/L compared with 337 Ϯ 214 units/L in newborns. At that time, we were unable to explain these findings. One year later, we repeated the study and obtained similar results. All mothers were familiar with the aim of the study and gave informed consent. Of the fourteen 3-month-old infants in the study, 8 had low serum IgoxLDL, but 6 subjects had extremely high values. In this study, we had the opportunity to analyze the records of these infants in detail. Surprisingly, the infants with extremely high IgoxLDL had not been breast-fed during the first 3 months of life, whereas the others had been (Table 1). The difference between the values in breast-fed and formula-fed infants was statistically significant (P Ͻ0.001, Wilcoxon unpaired test). The Spearman rank correlation between IgoxLDL concentrations in the sera of mothers and their newborns was statistically significant (r ϭ 0.79; P Ͻ0.001); on the other hand, no significant correlation was found between values for 3-month-old infants and their mothers. The early correlation reflects transplacental transport of class G IgoxLDL, whereas the infants were later able to produce their own antibodies. The production rate was individual and could be influenced by nutrition type. We also compared the number of DNA breaks in peripheral lymphocytes from 3-month-old infants by single-cell gel electrophoresis (comet assay). This method in combination with en-donuclease III (endoIII) treatment of cells is able to detect oxidized py-rimidines (2). When compared with breast-fed infants, formula-fed infants had a higher number of DNA strand breaks (0.39 Ϯ 0.06 vs 0.14 Ϯ 0.02 DNA strand breaks/10 9 Da) and endoIII-sensitive sites representing predominantly oxidized pyrimidines (0.24 Ϯ 0.10 vs 0.07 Ϯ 0.04 endoIII sites/10 9 Da; P ϭ 0.027 and 0.007, respectively, Mann–Whitney). Because the nutrition of infants …