Primary diffuse large B cell lymphoma of the stomach: analysis of somatic mutations in the rearranged immunoglobulin heavy chain variable genes indicates antigen selection.
Gastric low grade MALT lymphomas show a pattern of somatic mutations in their rearranged immunoglobulin genes, indicative of antigen selection. This provides evidence for antigen stimulation in the lymphomagenesis. Gastric diffuse large B cell lymphomas develop secondary to low grade MALT lymphoma or de novo. To study whether antigen-selection is also a feature of primary diffuse large B cell lymphomas, we analysed somatic mutations in the rearranged immunoglobulin heavy chain (IgH) variable genes (VH). The rearranged VH genes of six cases of gastric primary diffuse large B cell lymphoma were amplified from genomic or complementary DNA by a VH gene family-specific polymerase chain reaction method. The PCR products were directly sequenced and were compared to published germline sequences to analyse somatic mutations. Similarly to low grade MALT lymphomas 5/6 primary diffuse large B cell lymphomas show a pattern of somatic mutation in their rearranged VH genes, indicative of antigen selection and suggesting a role for antigens in lymphomagenesis. One case showed bi-allelic VH gene rearrangements, which were non-functional due to extensive deletions. Antigen selection could not be demonstrated or excluded. Antigen selection is a common feature in most analysed primary diffuse large B cell lymphomas, although some heterogeneity in the mechanisms involved in the lymphomagenesis of gastric primary diffuse large B cell lymphomas has not been excluded entirely (case 4).
Department of Pathology, University Hospitals, KU Leuven, Belgium.
A
A
Driessen
A
A
Tierens
N
N
Ectors
M
M
Stul
S
S
Pittaluga
K
K
Geboes
J
J
Delabie
C
C
De Wolf-Peeters
D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000235:genetics; D001483:Base Sequence; D005260:Female; D015321:Gene Rearrangement; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D016130:Immunophenotyping; D016393:Lymphoma, B-Cell / Q000235:genetics*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics*
D000951:Antigens, Neoplasm; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region