Optimizing Flow Cytometric Analysis of Immune Cells in Samples Requiring Cryopreservation from Tumor-Bearing Mice.
J Immunol
; 207(2): 720-734, 2021 07 15.
Article
in English
| MEDLINE | ID: covidwho-1311404
ABSTRACT
Most shared resource flow cytometry facilities do not permit analysis of radioactive samples. We are investigating low-dose molecular targeted radionuclide therapy (MTRT) as an immunomodulator in combination with in situ tumor vaccines and need to analyze radioactive samples from MTRT-treated mice using flow cytometry. Further, the sudden shutdown of core facilities in response to the COVID-19 pandemic has created an unprecedented work stoppage. In these and other research settings, a robust and reliable means of cryopreservation of immune samples is required. We evaluated different fixation and cryopreservation protocols of disaggregated tumor cells with the aim of identifying a protocol for subsequent flow cytometry of the thawed sample, which most accurately reflects the flow cytometric analysis of the tumor immune microenvironment of a freshly disaggregated and analyzed sample. Cohorts of C57BL/6 mice bearing B78 melanoma tumors were evaluated using dual lymphoid and myeloid immunophenotyping panels involving fixation and cryopreservation at three distinct points during the workflow. Results demonstrate that freezing samples after all staining and fixation are completed most accurately matches the results from noncryopreserved equivalent samples. We observed that cryopreservation of living, unfixed cells introduces a nonuniform alteration to PD1 expression. We confirm the utility of our cryopreservation protocol by comparing tumors treated with in situ tumor vaccines, analyzing both fresh and cryopreserved tumor samples with similar results. Last, we use this cryopreservation protocol with radioactive specimens to demonstrate potentially beneficial effector cell changes to the tumor immune microenvironment following administration of a novel MTRT in a dose- and time-dependent manner.
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Melanoma, Experimental
/
Leukocytes, Mononuclear
/
Cryopreservation
/
Myeloid Cells
/
Flow Cytometry
Type of study:
Cohort study
/
Experimental Studies
/
Observational study
/
Prognostic study
Topics:
Vaccines
Limits:
Animals
Language:
English
Journal:
J Immunol
Year:
2021
Document Type:
Article
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