Charakterisierung des Immunzellinfiltrats im Vestibularisschwannom

Vestibular schwannoma (VS) is the most common benign tumor in the cerebellopontine angle. Macrophage infiltration has been suggested to influence disease progression in our preliminary studies. In comparison, the infiltration of other immune cells in the VS is not well investigated. Therefore, the aim of this study was to characterize the immune cell infiltrate quantitatively and topologically in the VS.

Cryosections of five tumor samples from VS patients with different tumor volume were examined. The abundance of 18 immune cell markers and two tumor markers were detected using multi-epitope ligand cartography, which can be used to stain over 100 antigens on a tissue section. The microscopic images were subsequently analyzed using ImageJ and CellProfiler software.

In addition to S100B⁺ and CD56⁺ VS tumor cells, numerous CD68⁺ and CD163⁺ macrophages were visualized in the image sections. CD14⁺, CD16⁺, and CD40⁺ macrophages were also detected in the histological sections. Double positive cells were shown for CD3 and CD4 as well as CD3 and CD8, representing T helper cells and cytotoxic T cells. In addition to these T cell markers, CD80⁺, CD86⁺, and CTLA4⁺ cells were also identified, which might play a role in immune escape by tumor cells. Furthermore, detection of cells that were stained with antibodies against PD1 and PDL1 were observed.

From the fluorescence microscopic images, it can be concluded that more distinct immune cells are found in the VS than previously known. In addition to tumor-associated macrophages, proinflammatory and immature macrophages, T helper cells and cytotoxic T cells were detected. Likewise, the results indicate that immune cells may influence each other in activity and function. Thus may contribute to the development and proliferation of VS. Overall, these new findings offer the possibility to establish new diagnostic and therapeutic options in VS.