The effect of different isolation Methods on the number and surface expression of phenotypic markers and checkpoint receptors of tumor-infiltrating lymphocytes

Introduction Tumor infiltrating lymphocytes (TIL) have become the focus of oncological research in recent years. Significant research approaches of new immunological therapies aim at influencing the TIL in order to achieve an effective antitumoral effect. For the analysis of the TIL different isolation Methods are used for further investigations (FACS, ELISA, etc.).

Material and Methods We used various isolation processes (purely mechanical, enzymatic and enzymatic with the addition of fetal bovine serum) in patients with head and neck carcinomas. For the further processing, the tumor samples of the individual patients were divided and processed differently. This was followed by an individual comparison of the number of vital isolated lymphocytes. Additionally took place the flow cytometric analysis of surface expression of phenotypic markers (e.g., CD3, CD4, CD19) and expression of checkpoint molecules (e.g., PD-1, CTLA-4).

Conclusions The isolation process has a significant effect on the number and surface expression of tumor-infiltrating lymphocytes. The enzymatic isolation causes a higher number of TIL, but in part has a negative effect on the expression of the examined surface markers. The addition of FBS in the enzymatic digestion can partially reduce this negative effect, without significant negative impact on the number of isolated lymphocytes.

Conclusion The isolation process has a decisive influence on the quantity and quality of the isolated lymphocytes. This has to be taken into account in the analysis and interpretation of the Results of all studies with isolated TIL and thus has consequences for a relevant proportion of current and future oncological research.

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Publication History

Article published online:
10 June 2020