Antigenic phenotyping of lymphoid cells and B cell gene rearrangement in type B gastritis and in gastritis not associated with Helicobacter pylori colonization

Marginal-zone B cells of the mucosa-associated lymphoid tissue (MALT) are t he normal counterpart of the neoplastic cells in MALT lymphoma. In both cas es these lymphocytes express surface immunoglobulins, but are negative when stained for B cell associated antigens like CD10 and CD23. Furthermore, th e B cell gene rearrangement has been found in Helicobacter pylori associate d chronic gastritis and in extranodal type of marginal-zone lymphoma. The a im of this study was to quantify the number of IgM-, CD10-, and CD23-positi ve lymphocytes in patients with type B gastritis and to compare the results with the antigen profile of mononuclear cells in patients with gastritis n ot associated with H. pylori. Additionally, the immunoglobulin heavy-chain (IgH) gene rearrangement in H. pylori positive and H. pylori negative gastr itis was studied. From 23 patients with a positive urease test and/or histo logically proven H. pylori infection and chronic gastritis and from 22 pati ents with H. pylori negative chronic gastritis mucosa biopsy specimens were taken. Single-cell suspensions were obtained following enzymatic digestion . For immunocytochemistry, an alkaline phosphatase-antialkaline phosphatase method was applied. IgH gene rearrangement in formalin-fixed, paraffin-emb edded specimens was determined by polymerase chain reaction in 11 patients with chronic gastritis. An increase in mu-positive plasma cells and B lymph ocytes was detected in patients with H. pylori positive gastritis as compar ed with patients with H. pylori negative gastritis (10.0 vs. 3.9%, p < 0.00 1, and 4.3 vs. 1.6%, p < 0.01, respectively). In both groups, the proportio n of CD10- and CD23-positive lymphocytes was <1%. IgH gene rearrangement wa s not restricted to type B gastritis; single bands were also present in 3 o f 7 patients with H. pylori negative chronic gastritis. Our finding of IgH gene rearrangement in some of the patients with H. pylori negative chronic gastritis indicates that additional factors may be critical for these genot ypical changes and for the pathogenesis of gastric MALT lymphoma.