Incidence of novel N-glycosylation sites in the B-cell receptor of lymphomas associated with immunodeficiency.

Novel N-glycosylation sites are introduced by somatic mutation into the V genes of the majority of follicular lymphomas. Sites are positively selected and rare in normal memory B cells, indicating a potential role in tumour survival in the germinal centre (GC). The incidence of c. 40% in diffuse large B-cell lymphomas (DLBCL) parallels the known heterogenity of the disease. Immunodeficiency-related non-Hodgkin's lymphomas (NHL) include post-transplant lymphoproliferative disorders (PTLD) and acquired immunodeficiency syndrome-related NHL (AIDS-NHL). Most PTLD derive from B cells that carry mutated V-H genes and that have completed the GC reaction. All AIDS-NHL carry mutated V-H genes and variable features of GC or post-GC cells. To determine if N-glycosylation is a feature of immunodeficiency-related lymphomas, we analysed the V-H genes of 19 PTLD and 36 AIDS-NHL. Novel sites were rare in PTLD (4/19), similar to memory B cells (P=0.15). AIDS-NHL, including DLBCL and Burkitt's lymphomas (BL), showed heterogeneity with 16 of 36 (44%) having novel sites. The findings indicate no selection of N-glycosylation sites in PTLD, consistent with post-GC features. The variable incidence of N-glycosylation sites in AIDS-NHL mirrors that in DLBCL and sporadic BL of immunocompetent hosts, supporting the known heterogeneity of these disorders, and possibly pointing to distinct routes of tumour development.