This is an update to the Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition), Chapter 3: 12C, by Cossarizza et al. Administration of anti-ARTC2 nanobody(S+16a) prevents cell death during tissue processing. We demonstrate that the phenotype of CD44midTreg is significantly impacted, whereas the eTreg phenotype remains stable following S+16a treatment, outlining specific protocols for population recovery.