Expression of CD86 and increased infiltration of NK cells are associated with Helicobacterpylori-dependent state of early stage high-grade gastric MALT lymphoma

AIM： A high percentage of early-stage high-grade gastric mucosa-associated lymphoid tissue （MALT） lymphomas remain Helicobacter pylori （ H pylori）-dependent. However,unlike their low-grade counterparts, high-grade gastric MALT lymphomas may progress rapidly if unresponsive to H pylori eradication. It is mandatory to identify markers that may predict the H pylori-dependent status of these tumors. Proliferation of MALT lymphoma cells depends on cognate help and cell-to-cell contact of H pylori- spedfic intratumoral T-cells. To examine whether the expression of co-stimulatory marker CD86 （B7.2） and the infiltration of CD56 （＋） natural killer （NK） cells can be useful markers to predict Hpylori-dependent status of high-grade gastric MALT iymphoma. METHODS： Lymphoma biopsies from 26 patients who had participated in a prospective study of Hpylori-eradication for stage IE high-grade gastric MALT lymphomas were evaluated. Tumors that resolved to Wotherspoon grade Ⅱ or less alter H pylori eradication were dassified as H pylori-dependent; others were dassified as H pylori-dependent.The infiltration of NK cells and the expression of CD86 in pre-treatment paraffin-embedded lymphoma tissues were determined by immunohistochemistry. RESULTS： There were 16 H pylori-dependent and 10 H pylori-independent cases. CD86 expression was detected in 11 （68.8%） of 16 H pylori-dependent cases but in none of 10 H pylori-independent cases （P = 0.001）.H pylori-dependent high-grade gastric MALT lymphomas contained significantly higher numbers of CD56 （＋） NK cells than H pylori-independent cases （2.8±1.4% vs 1.1±0.8%, P = 0.003）. CD86 positive MALT lymphomas also showed significantly increased infiltration of CD56 （＋） NK cells compared to CD86-negative cases （2.9±1.1% vs 1.4±1.3%; P= 0.005）. CONCLUSION： These results suggest that the expression of co-stimulatory marker CD86 and the increased infiltration of NK cells are associated with Hpylori-dependent state of early-stage high-grade gastric MALT lymphomas.