CD19 and follicular lymphoma: Furthermore, in a limited number of frozen DLBCL, low-grade NHL and follicular lymphoma specimens (in which the anti-CD19 epitope is preserved), we were able to confirm by dual label immunofluorescence (Fig S5) that CD21 was co-expressed in the same cells as CD19 in approximately two-thirds of cases, with lower intensity in approximately half of those, and no expression in the remaining one-third of cases (Table IIB).