N-linked mannoses in the antigen-binding site of GCB-DLBCL are susceptible to treatment with Endo H. The glycosylation patterns of GCB-DLBCL primary samples (known to have AGSs in the CDRs) and peripheral blood mononuclear cells (PBMCs) from healthy donors were analyzed by digestion with Endo H (which cleaves mannose only) or PNGase F (which removes all glycans) after biotinylation and isolation of the cell surface proteins. Primary anti-µ or anti-γ antibodies were used to detect the surface Igµ (16-TB0006 and 17-TB0084 primary samples) or Igγ heavy chains (12-TB0153 and 16-TB0014) by immunoblotting, respectively. Numbers on the left of each gel indicate the molecular weight in kD of the reference ladder. The characteristics of the primary samples are described in supplemental Table 6. The glycosylation pattern of DLBCL cell lines with or without AGS in the CDR is shown in supplemental Figure 4.