Fig. 4.

Heatmap of 73 healthy donors. 73 serum samples from healthy donors were processed on the 330,000 immunosignature array. No statistical tests were performed. Rather, a random sample of 100,000 peptides were hierarchically clustered using Euclidean distance as the separation metric on both the Y-axis (peptides) and X-axis (human donors). A five-group k-means clustering was also performed on the peptides. Results of the k-means cluster were used to color the dendrogram arms. Two k-means groups of peptides are highlighted. The blue group shown immediately left of the heatmap represents a group of peptides common across at least 26 healthy volunteers. The three amino acid sequence PAD/PLD/PDN appears commonly in the blue group. At least 10 donors shared peptides from the magenta group, but motifs in these peptides are more cryptic than the blue group. In the absence of disease-specific peptides, healthy donors can group by common antibody reactivity.