Background/Objectives: Vestibular schwannoma (VS) is the most common benign tumor in the cerebellopontine angle. In preliminary studies, macrophage infiltration has been suggested to influence disease progression. However, the infiltration of other immune cells in VS remains largely unexplored. The aim of this study was to comprehensively characterize the immune cells in sporadic VS. Methods: Cryosections of five tumor samples from VS patients with different tumor volumes were examined. The abundance of fourteen immune-cell markers, one vascular marker, and two tumor markers were detected using multi-epitope ligand cartography (MELC). This enabled the spatial distribution and colocalization of immune- and tumor cell markers to be examined. Furthermore, using qPCR and bulk RNAseq, the mRNA levels of the immune-cell markers were examined in 204 VS samples of different tumor sizes. Results: VSs with greater tumor volumes showed an increased number of immune cells, more precisely T-helper cells (TH cells), cytotoxic T cells (Tc cells), CD68+, and CD163+ macrophages, as well as CD279+ (PD-1) and CTLA4+ cells (p < 0.05). In addition, an increased number of CD274+ (PD-L1) tumor cells were detected in VSs with higher tumor volume (p < 0.05). Conclusions: These results indicate that an increased diversity of immune-cell subtypes influences VS tumor size. Thus, novel diagnostic and therapeutic options could be developed by targeting the tumor-associated immune-cell populations in VSs.
Becker et al. (Fri,) studied this question.