Fig. 7: Rise in IgG binding with age.

For each post-birth timepoint, the change in IgG binding to each protein (classified as described in Fig. 2) since the previous sample in each individual (n = 63) was calculated. This was compared with the relative strength of the IgG response in the previous sample, which was calculated by subtracting the population-wide mean response to the protein from the individual’s response to the protein. Each point represents an analysis of a protein in an individual at a defined timepoint. The black lines show the linear models that were fitted to each protein type at each post-birth timepoint. The correlation statistics shown on each panel were calculated using two-tailed Pearson’s correlation tests. In the context of the neonatal decline in IgG levels, the negative correlations show that the largest declines in IgG binding between birth and 6 mo reflect the proteins that were most strongly bound by IgG in the mother. In the context of the emerging endogenous antibody repertoire, the largest increases in IgG binding post-6 mo reflect relatively weak IgG responses in an individual rising towards the level observed across the rest of the cohort. Source data are provided as a Source Data file.