CD37 and B-cell non-Hodgkin lymphoma: Importantly, using flow cytometry analysis, we observed the presence of surface markers related to malignant B-cell lineages such as CD19 and CD20, which is consistent with previous studies that show that different B-cell surface proteins (CD19, CD20, CD24, CD37 and HLA-DR) are expressed on EXOs from B-cell lymphoma cell lines [7, 39].