Surface expression of CD19, CD20, CD22, and CD37 in multiple subtypes of B-NHL. Flow cytometry was used to analyze single-cell suspensions from FL, DLBCL, MCL, CLL, and MZL, as well as tonsils from healthy donors. Tumor cells were identified by gating on CD3⁻CD20⁺ B cells, followed by gating on tumor-restricted Ig light chain (Ig light chain–negative B cells in some cases). (A) Expression of CD37, CD19, CD20, and CD22 in tumor cells from NHL patients and in B cells from healthy donor tonsils. Relative protein expression was calculated through Cytobank using arcsinh transformation of median fluorescence intensity (MFI) of the cell population of interest as follows: fold change = arcsinh (MFI of protein in B cells/scale argument) − arcsinh (MFI of protein in T cells/scale argument). FL: n = 5 or n = 18 (CD19 and CD20), DLBCL: n = 18, MCL: n = 10, CLL/MZL: n = 8, tonsils: n = 8 or n = 15 (CD19 and CD20). (B) Association of CD37 and CD19 tumor cell expression levels in B-NHL. (C) Examples of CD19 and CD37 expression in tumor cells from 3 DLBCL patients. (D) Percent expression of CD19 and CD37 in individual samples from NHL patients. *P < .05, **P < .01, ****P < .0001, Mann-Whitney U nonparametric test.