Introduction:
The head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent malignant
disease worldwide. The current treatment includes surgery and/or radiation therapy,
radiochemo- and antibody therapy. Immune cell infiltration is one important determinant
of patient survival. Immunotherapy with checkpoint inhibitors gained growing interest
in tumor therapy and immune cell infiltration may play a role for successful therapy.
The focus of our study was to investigate the heterogeneity of immune cell infiltration
in different regions of HNSCC biopsies. We focused on regulatory T cells, antigen
presenting cells, and the expression of costimulatory as well as inhibitory molecules
on tumor infiltrating T cells.
Methods:
We analyzed biopsies from different tumor regions and corresponding healthy mucosa
of 30 patients by flow cytometry.
Results:
Comparing tumor tissue with corresponding healthy mucosa, we observed a significant
decrease in the number of intra-tumoral CD4+ as well as CD8+ T cells while different
types of myeloid cells, especially neutrohilic granulocytes, were massively increased.
The comparison of the immune cell populations in different tumor regions, revealed
no significant differences. Also the expression of activation markers (e.g. CD69)
and checkpoint molecules (e.g. PD-1) on tumor infiltrating lymphocytes was not altered
between biopsies from different localisations, also activation and distribution of
myeloid cells showed no significant variation.
Conclusion:
In conclusion, our results show that HNSCC are characterized by a massive infiltration
with neutrophilic granulocytes and low numbers of lymphocytes. This feature was similar
between different tumor regions indicating no intra-tumoral heterogeneity in immune
cell infiltration.
