The cell-to-cell heterogeneity of PD-1, PD-L1 and PD-L2 expression among cells from NHL biopsies can now be assessed by single cell RNA-sequencing technologies, but these are not widely available in diagnostic laboratories so the current clinical need is for an IHC-based test to detect cell surface protein markers. Here, PDCD1LG2 is linked to non-Hodgkin lymphoma.