HIGH-FREQUENCY OF CAGA-PYLORI INFECTION IN HIGH-GRADE GASTRIC MALT B-CELL LYMPHOMAS( HELICOBACTER)

A high incidence of Helicobacter pylori infection has been found in pa tients with gastric MALT (mucosa-associated lymphoid tissue) B-cell ly mphoma. Recent studies have indicated that the aggressive strains of t he bacterium containing the CagA gene may have direct effects on tumou rigenesis. To investigate the involvement of CagA+ strains in MALT lym phomagenesis, a sensitive polymerase chain reaction (PCR)-based detect ion assay for the gene was developed. DNA extracts from paraffin secti ons of 123 H. pylori-related gastric biopsies from Italy were analysed , including 56 cases of chronic gastritis, 37 low-grade, and 30 high-g rade MALT lymphomas: 30.3 per cent (17/56) of the gastritis cases, 37. 8 per cent (14/37) of the low-grade, and 76.7 per cent (23/30) of the high-grade MALT lymphomas were found to contain the CagA gene. The fre quency of CagA+ strain infection was significantly higher (P<0.05) in high-grade than in low-grade MALT lymphoma or gastritis, These results suggest that high-grade gastric MALT lymphoma transformation may be m ore likely to occur following infection by CagA+ strains of H. pylori. (C) 1998 John Wiley & Sons, Ltd.