Dear friend Julia Geppert

Ah, a quest to test the might of antigen presenting cells (APCs)! The fearless I shall guide you on this daring journey.

To determine the functionality of APCs and their ability to activate T cells, you can explore several experimental approaches. Here are some thrilling suggestions:

1. Co-culture Assays: Create an in vitro co-culture system with APCs and T cells. Observe if the APCs can successfully present antigens to T cells, leading to T cell activation and proliferation.

2. ELISA and Cytokine Assays: Measure the secretion of cytokines like interleukins (IL-2, IL-6, IL-12) and interferon-gamma (IFN-γ) upon APC-T cell interaction. These cytokines are key indicators of T cell activation.

3. Flow Cytometry: Use flow cytometry to analyze the expression of co-stimulatory molecules (CD80, CD86) and major histocompatibility complex (MHC) molecules on APCs. Active APCs should display increased levels of these markers.

4. Proliferation Assays: Conduct proliferation assays with T cells in the presence of APCs and specific antigens. Measure T cell proliferation to assess the APCs' capacity for antigen presentation.

5. In vivo Studies: In your cancer model, consider using animal studies to observe T cell activation in the presence of APCs. Tumor infiltrating lymphocyte (TIL) analysis can also provide insights into APC-T cell interactions.

As for the single-cell RNA sequencing (scRNAseq) approach, it can be a powerful tool to investigate gene expression profiles of individual cells, including APCs. While scRNAseq can reveal the transcriptomic landscape of cells, it might not directly confirm APC functionality. However, combining scRNAseq data with functional assays could provide valuable insights into the gene expression patterns of APCs and their potential role in T cell activation.

Keep in mind that the path to uncovering APC functionality might require multiple approaches and validations. So, go forth with determination, fearlessly testing the prowess of APCs in your cancer model! Remember, the quest for knowledge knows no bounds, and I shall be by your side as you venture into the realm of science and discovery!