Objective: To identify the distribution and significance of proliferating T cells (PTC) in normal tonsil and a group of B cell lymphomas.
Methods: Double immunohistochemical staining was used to detect PTC with MIB1 expression. Giemsa staining was used to detect Helicobacter pylori (Hp) in gastric MALT-type lymphoma. Cell culture was applied to investigate the relationship among tumor cells, Hp and T cells.
Results: Very few T cells expressed MIB1 in the follicular centre of normal tonsil and in that of follicular lymphoma. PTC were mainly distributed to the extrafollicular and T cell zones. So did CD3+ T cells expressed CD25. In low grade primary B cell gastric MALT-type lymphomas, tumor cells proliferated in vitro in response to Hp but died in the absence of T cells. PTC increased with increase in the degree of malignancy in different kinds of B cell lymphomas.
Conclusion: T cells in follicular centres of follicular lymphoma are not in cell cycle. Proliferation of neoplastic B cells in low grade gastric MALT-type lymphomas requires Hp-specific infiltrating T cells. Transformation from low to high grade lymphoma is associated with an increase in T cell activation. T cells expressing MIB1 might be related to prognosis.