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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 VH genes and that have completed the GC reaction. All AIDS-NHL carry mutated VH 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 VH 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. [ABSTRACT FROM AUTHOR]

Neoangiogenesis is an integral component of bone marrow myeloproliferation in patients with myelofibrosis with myeloid metaplasia (MMM). As extramedullary haematopoiesis is a constitutive feature of MMM, we studied spleen neoangiogenesis by a computerized image analysis in MMM patients. Compared with five normal subjects, spleen CD34-staining capillary vascular density (CVD) was 2.1-3.03 times higher than the upper range of normal in six of the 15 (40%) MMM patients. CD8-staining sinusoidal vascular density (SVD) was constantly normal or lesser than normal and was inversely correlated with CVD (R = -0.53; P = 0.04). In MMM patients who did not receive cytoreductive or radiation therapy in the month before splenectomy (n = 9), the CVD was a significant determinant of spleen size (R = 0.88; P = 0.04). In MMM patients, the number of spleen CD34+ haematopoietic stem cells was increased from 1.2 to 98 times the upper limit of normal, and predicted the expansion of CVD (R = 0.57; P = 0.03). A population of cells expressing the CD34+/CD133+/VEGFR-2+ angiopoietic phenotype was present in the blood and spleen of five of seven patients. These results document that neoangiogenesis is an integral component of spleen re-localization of haematopoietic stem cells and suggest a cellular mechanism for spleen neoangiogenesis.