SEQUENCE-ANALYSIS OF IMMUNOGLOBULIN VARIABLE REGION GENES THAT ENCODEAUTOANTIBODIES EXPRESSED BY LYMPHOMAS OF MUCOSA-ASSOCIATED LYMPHOID-TISSUE

Aim-To determine whether the immunoglobulin genes used by three gastri c mucosa associated lymphoid tissue type lymphomas with known autoreac tivity are mutated from germline as mutation from germline is an indic ator of exposure to a mutational mechanism which characteristically ac ts on B cells as they undergo a follicle centre response. Methods-Cell lines established from two cases of MALT type lymphoma secrete autoan tibodies recognising follicular dendritic cells (one case) and basemen t membrane (one case). The immunoglobulin heavy chain variable region genes (IgV(H)) and light chain variable region genes (IgV(L)) used by these cell lines, and the IgV(H) genes from a third case recognising h uman IgG were sequenced. Results-All three cases studied had mutated I gV(H) genes, while the IgV(L) genes were unmutated. Conclusion-The pre sence of mutations in IgV(H) genes is consistent with the origin of ga stric MALT type lymphomas from B cells which have traversed the lympho id follicle.