Sequencing analysis of 15 primary breast cancers identified somatically acquired mutations in tumor-infiltrating leukocytes. (a) Gating scheme for fluorescent-activated cell sorting of CD45-positive hematopoietic cells. DAPI was included as live-dead stain. Cell doublets were excluded prior to gating on APC-Cy7 (not shown). DNA extracted from the CD45-positive fraction was analyzed using three independent sequencing platforms. (b) Representative integrated genomics viewer image showing the presence of acquired mutations. Reads that do not match the reference nucleotide are colored. Gray bar chart on top displays the read depth. Reference nucleotide and protein sequence are depicted for each mutation. Variant allele frequency (VAF) and the number of altered and total reads are shown (alt|total, VAF). DAPI, 4′,6-diamidino-2-phenylindole; GFP, green fluorescent protein.