Aaron D. Therien, MS, BS
Research Technician II
Duke University Medical Center, United States
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
B cells are becoming increasingly recognized as key regulators of immune responses in melanoma. We aimed to explore differences in the histologic location and activation status of B cells in sentinel lymph nodes (SLN) of melanoma patients at initial diagnosis.
Methods:
Paraffin slides from 8 patients with tumor in the SLN (pSLN) and 16 without tumor (nSLN) underwent NanoString Digital Spatial Profiling®. After staining with fluorescent markers for CD20 (B cells), CD3 (T cells), CD11c (antigen presenting cells) and a nuclear marker (tumor) was performed, regions of interest (ROI) were selected based on location of B cell regions (germinal follicles) (Figure 1). A panel of 62 proteins was then analyzed from the ROIs. Quality control analysis was performed on protein values prior to analysis.
Results:
First, we examined differences between B cell regions from patients with pSLN and nSLN. Patients with pSLN had significantly higher expression of PD-1, CD27, and CD80 compared to patients with nSLN. Among 8 patients with pSLN, we noted two patterns of B cell arrangement, either surrounding the tumor deposit or infiltrating the tumor (Figure 1). The infiltrative pattern was associated with prolonged recurrence free survival (RFS). Furthermore, B cells in close proximity to tumor had a protein profile suggesting marked immune activation compared to B cell regions in that were farther away.
Conclusions:
Spatial biology can be a valuable tool in evaluation of the tumor microenvironment. B cell activation may be important even at early stages of melanoma in regulating tumor progression.