Gastric mucosa as an additional extrahepatic localization of hepatitis C virus: viral detection in gastric low-grade lymphoma associated with autoimmune disease and in chronic gastritis.

The hepatitis C virus (HCV) has been linked to B-cell lymphoproliferation and autoimmunity, and has been localized in several tissues. The clinical observation of an HCV-infected patient with Sjögren's syndrome (SS) and Helicobacter pylori (HP) positive gastric low-grade B-cell non-Hodgkin's lymphoma (NHL), which did not regress after HP eradication, led us to investigate the possible localization of HVC in the gastric microenvironment. HCV genome and antigens were searched in gastric biopsy specimens from the previously mentioned case, as well as from 9 additional HCV-infected patients (8 with chronic gastritis and 1 with gastric low-grade B-cell NHL). HCV-specific polymerase chain reaction (PCR) and immunohistochemistry procedures were used. The gastric B-cell NHL from the patient with SS was characterized by molecular analyses of B-cell clonality. HCV RNA was detected in both the gastric low-grade B-cell NHL and in 3 out of 6 gastric samples from the remaining cases. HCV antigens were detected in the residual glandular cells within the gastric B-cell NHL lesions, in glandular cells from 2 of the 3 additional gastric lesions that were HCV positive by PCR, and in 1 additional chronic gastritis sample in which HCV-RNA studies could not be performed. By molecular analyses, of immunoglobulin genes, the B-cell NHL from the patient with SS was confirmed to be a primary gastric lymphoma, subjected to ongoing antigenic stimulation and showing a significant similarity with rheumatoid factor (RF) and anti-HCV- antibody sequences. Our results show that HCV can localize in the gastric mucosa.