Serum soluble Fas antigen in gastric MALT (mucosa-associated lymphoid tissue) lymphoma patients

We measured the serum level of soluble Fas (sFas) antigen in gastric MALT (mucosa-associated lymphoid tissue) lymphoma patients to investigate immune response of B lymphoma cells in gastric MALT lymphoma. The serum sFas antigen levels in 21 patients with Helicobacter pylori (HP)-positive MALT lymphoma were 4.51+/-0.25 (mean+/-SD) in the high grade malignant group (n=9) that demonstrated diffuse large cell (DL) components and 2.53+/-0.46 (mean+/-SD) in the low grade malignant group (n=12) that did not demonstrate DL components. Among 12 patients who underwent HP eradication therapy, the blood sFas antigen level lowered after eradication in 7 out of 10 patients who showed complete response or partial response, while sFas antigen level did not decrease in the 2 patients who showed no change or progression of the disease. In the high grade malignant group, 2 of 3 patients who underwent HP eradication treatment showed a mild decrease in the sFas antigen level as well as an improvement on endoscopic and histological examinations, but these sFas level were not normalized. The blood sFas antigen level tended to coincide with pathological activity and malignancy, suggesting that the sFas antigen level may be a prognostic indicator and useful index for the response of HP eradication treatment in gastric MALT lymphoma.