Serial phenotypic analysis of mouse peripheral blood leukocytes

Repeated phenotypic analysis of mouse peripheral blood leukocytes over short periods of time (2 weeks) has been difficult because of the very limited volumes of blood available under guidelines of the Institutional Animal Care and Use Committee. The loss of leukocytes and variations among laboratories during conventional flow cytometry sample preparation based on lysing and repeated washing have been limiting factors when measuring multiple parameters in small samples. We describe a method of phenotypic analysis using a no-lyse, no-wash staining technique combined with fluorescent triggering for data collection that can be performed on volumes of 20 muL or less of whole blood per set of markers in one tube. This method allows repeated phenotypic analysis of peripheral whole blood from mice. Fluorescent triggering with anti-CD45-PE/Cy5 antibody allows high-quality phenotypic data to be collected for CD4, CD8, TcR- beta, CD45R (B220), CD11b, and Gr-1 epitopes on leukocytes from mouse peripheral blood without lysis. The markers selected cover the major populations in peripheral mouse blood. Reproducibility and time-course data are presented for sampling periods as long as 4 weeks. Data produced by flow cytometers manufactured by two different companies show well-correlated results. An instrument equipped with a gated amplifier or a photomultiplier tube suitable for Cy7 conjugates could measure additional parameters. Because of interference from unlysed erythrocytes, scatter parameters are not useful for identifying cell populations with this method.