Isolation of mouse CD45 positive leukocytes from tissues

Abstract Immune cell function is often tissue-specific, therefore isolating cells from their tissue microenvironment is necessary to better understand their role in health and disease. This can be challenging in the presence of non-immune, tissue-derived cells and cellular debris from tissue dissociation. These factors reduce the leukocyte start frequency, which can prolong the isolation process and limit the identification of small but critical leukocyte subsets. To overcome these obstacles, we developed a simple and rapid selection method to enrich for CD45+ leukocytes from mouse tissues. Starting with a single cell suspension, cells are labelled with an antibody complex that links CD45+ cells to magnetic particles and following magnetic separation, the isolated CD45+ cells are ready for use. Using healthy mouse lung tissue as an example, CD45+ leukocytes were enriched from 63.5 ± 9.4% to 97.1 ± 1.2% purity, and the recovery of viable CD45+ cells was 37.7 ± 14.5% (mean ± SD, n=37). Preliminary testing on tumors from a mouse 4T1 breast tumor model resulted in efficient enrichment of tumor-infiltrating leukocytes. Importantly, the composition of immune subsets from both healthy lung tissues and tumor samples was maintained following CD45 selection. To demonstrate functionality, T cells within the CD45 selected population from spleen were able to upregulate CD25 and CD69, and proliferate upon stimulation. In as little as 20 minutes, the EasySep™ Mouse CD45 Isolation Kit allows researchers to easily enrich for functional leukocytes from tissue samples. Examining immune cells directly from healthy and tumor tissues will enhance our understanding of how these cells function and aid in developing new approaches to combat disease progression.