Quantitation of calreticulin exposure associated with immunogenic cell death

Tumor cells treated by immunogenic cell death (ICD) inducers emit danger associated molecular patterns (DAMP), including but not limited to calreticulin (CALR), which translocates from the ER lumen to the surface of the cellular membrane where it serves as de novo uptake signal for antigen presenting cells of the immune system. CALR is exposed at an early stage of ICD and dictates tumor antigen transfer and therefore the immunogenicity of cancer cell death. Here, we provide a bi-color flow cytometry protocol for the quantification of ICD-associated CALR cell surface exposure in fixed samples. As compared to the detection of surface exposed CALR by confocal microscopy, the present flow cytometry-based analysis is cost-efficient and does not require sophisticated equipment. Moreover, the staining panel can be extended to a multicolor analysis for the parallel assessment of additional parameters.