Temporal stability of antibacterial maternal IgA reactivity within one childbirth/infant. Multiple milk samples were collected from different donors over time and analyzed with our flow cytometric array (Fig. 1 A). (A) Heat map of normalized antibacterial binding affinity of different donors. Hierarchical clustering (Spearman) of various donors is indicated by colored bars above and below the heatmap. Date of collection indicated on heatmap: D## = number of days after delivery of sample collection. Donor numbers indicated on top of each column. (B) Scatter graph showing the normalized antibacterial IgA binding values for each sample from longitudinally collected donors (each color represents a different donor; from A). (C and D) PCA of the aggregate antibacterial IgA binding of longitudinally collected samples. Each donor colored as in A. (C) PCA of individual longitudinally collected samples where symbols indicate the time of collection (week after delivery). (D) PCA from C where ellipses indicate the maximum variance for each donor cluster along each axis. No ellipses are drawn for samples where fewer than four samples were available. This figure is an aggregate of experiments on 33 samples from eight donors.