A Spatially Resolved Dark- versus Light-Zone Microenvironment Signature Subdivides Germinal Center-Related Aggressive B Cell Lymphomas

We applied digital spatial profiling for 87 immune and stromal genes to lymphnode germinal center (GC) dark- and light-zone (DZ/LZ) regions of interest toobtain a differential signature of these two distinct microenvironments. Thespatially resolved 53-genes signature, comprising key genes of the DZ mutationalmachinery and LZ immune and mesenchymal milieu, was applied to the transcriptomes of 543 GC-related diffuse large B cell lymphomas and double-hit (DH) lymphomas. According to the DZ/LZ signature, the GC-related lymphomas were subclassified into two clusters. The subgroups differed in the distribution of DH casesand survival, with most DH displaying a distinct DZ-like profile. The clusteringanalysis was also performed using a 25-genes signature composed of genes positively enriched in the non-B, stromal sub-compartments, for the first timeachieving DZ/LZ discrimination based on stromal/immune features. The reportoffers new insight into the GC microenvironment, hinting at a DZ microenvironment of origin in DH lymphomas.