Restricted V beta gene usage of tumour-infiltrating T lymphocytes in primary gastric malignant B-cell lymphoma.

Ten cases of primary gastric malignant lymphoma (PGL) were investigated by immunohistochemical and molecular genetic analysis. These cases were diagnosed histopathologically as follicular small cleaved cell type (1 case), diffuse small cleaved cell type (3 cases) and diffuse large cell type (6 cases) based on the WF (Working Formulation) classification. Seven cases classified as small cleaved or diffuse large cell type belong to low (4 cases) or high (3 cases) grade MALT lymphoma according to Isaacson's classification. All PGL belonged to B lineage cells according to immunohistochemical study and immunoglobulin rearrangements. Rearrangements of TCR beta chain genes were observed in four of the ten cases. The possibility that the TCR beta rearrangements were caused by tumour-infiltrating T-cells (TILs) was supported by the following observations: the tumours did not show T- and B-cell biphenotype, TCR beta exhibited functional VDJ rearrangement and V beta usage pattern was not a neoplastic type. Analysis of the repertoire of the TCR beta chain in TILs revealed a common usage of V beta 2 in the above four cases, and furthermore, predominant usage of a particular beta chain composed of V beta 2-D beta 2.1-J beta 2.3 was observed in one of the four cases. These results indicate that the TILs of PGL have a restricted TCR repertoire.