THE RESPONSE OF CELLS FROM LOW-GRADE B-CELL GASTRIC LYMPHOMAS OF MUCOSA-ASSOCIATED LYMPHOID-TISSUE TO HELICOBACTER-PYLORI

An association has been shown between colonisation of gastric mucosa b y Helicobacter pylori, acquisition of mucosa-associated lymphoid tissu e (MALT), and occurrence of primary B-cell gastric MALT lymphoma. We i nvestigated the immunological response of cells from 3 low-grade prima ry B-cell gastric MALT lymphomas to H pylori type NCTC 11637 and 12 is olates of H pylori from patients without lymphomas. After co-culture o f tumour cells with bacteria, cells were examined for phenotypic evide nce of activation and proliferation, and supernatant assayed to detect tumour-derived immunoglobulin and interleukin-2 (IL-2). Neoplastic B cells and non-neoplastic T cells proliferated, and IL-2-receptor expre ssion by most cells in the cultures was increased with stimulating str ains of H pylori. There were also increases in tumour immunoglobulin a nd IL-2 release when activation and proliferation were seen in respons e to stimulating bacteria. Removal of T cells from the tumour cell sus pension reduced proliferation and IL-2-receptor expression. In compari son, no responses were seen in cells from high-grade gastric MALT lymp homas or low-grade B-cell MALT lymphomas of other sites. The response of low-grade B-cell gastric MALT lymphomas to stimulating strains of H pylori is dependent on H-pylori-specific T cells and their products, rather than the bacteria themselves.