Abstract
Aim—To determine whether the immunoglobulin genes used by three gastric mucosa associated lymphoid tissue type lymphomas with known autoreactivity are mutated from germline as mutation from germline is an indicator of exposure to a mutational mechanism which characteristically acts on B cells as they undergo a follicle centre response. Methods—Cell lines established from two cases of MALT type lymphoma secrete autoantibodies recognising follicular dendritic cells (one case) and basement membrane (one case). The immunoglobulin heavy chain variable region genes (IgVH) and light chain variable region genes (IgVL) used by these cell lines, and the IgVH genes from a third case recognising human IgG were sequenced. Results—All three cases studied had mutated IgVH genes, while the IgVL genes were unmutated. Conclusion—The presence of mutations in IgVH genes is consistent with the origin of gastric MALT type lymphomas from B cells which have traversed the lymphoid follicle.