Stabilization of blood for long-term storage can affect antibody-based recognition of cell surface markers.

Whole-blood fixation provides a rapid and simplified method for cell preservation compared to isolation of peripheral blood mononuclear cells (PBMCs). This can be especially important for sample acquisition and storage in resource-limited settings. However, some caveats have been reported, such as reduced cell marker recognition. Here, we evaluated the whole-blood proteomic stabilizer PROT1 and compared recognition of 53 common cell markers in fixed buffy coats and cryopreserved PBMCs isolated from the same donor. Several antibodies completely lost their binding to the cells, while others presented with partial loss of marker recognition or no effect at all. Based on the screened antibodies, we designed two antibody panels allowing phenotyping of B cells, monocytes, and dendritic cells and also T cells and NK cells in both fixed and non-fixed material. Taken together, our observations suggest that antibodies intended to be used with fixed blood first need to be evaluated for marker recognition and staining intensity, in comparison with fresh samples or cryopreserved PBMCs.