Autoantigen receptors in extranodal non-Hodgkin B-cell lymphomas.

Extranodal lymphomas of B-cell origin show a biologic behavior different from nodal lymphomas and an unexplained preference of a specific histologic type, the so called MALT-type. The lymphoma cells of this type show specific colonization of lymphoid follicle centers and subepithelial plasma cell differentiation suggesting that the tumor is immunologically responsive in vivo to as yet unidentified signals. Their tumor immunoglobulin has been shown to recognize autoantigens but lacks reactivity with bacterial antigens. Recent studies provide certain evidence, that antigen may play a role in the pathogenesis of gastric MALT-type lymphoma. The malignant B cells responded to antigen-triggering in vitro and have undergone somatic hypermutation probably in response to antigen selection. Therefore it is possible, that the local stimulation of lymphoma-precursor B-cells triggered either by exogenous (e.g. Helicobacter pylori) or endogenous (e.g. autoantigen) antigen in co-operation with the reactive inflammatory infiltrates establishes the local tumor growth until further mutagenic alterations guide tumor development and progression.