Intra-tumoral cytolytic cells: pattern of distribution in B-cell non Hodgkin s lymphoma.

Non-Hodgkin s lymphomas (NHLs) constitute a heterogeneous group of lymphoid neoplasms and a majority of them in India are of B-cell phenotype. Varying numbers of T lymphocytes and natural killer (NK) cells are consistently present within the lymph nodes (LNs). The role of these reactive cells is becoming understood. TIA-1 is a cytotoxic granule associated RNA binding protein, the expression of which is restricted to cytotoxic T lymphocytes (CTLs) and NK cells. Snap frozen lymph node biopsies obtained from 41 B-cell NHLs were localized for intra-tumoral TIA-1 + cytolytic cells by immunohistochemistry. Distribution of T cell subsets and NK cells were also quantified. Cells expressing TIA-1 antigen was observed in all the cases, seen as a strong granular cytoplasmic signal. Results indicate significantly higher number of TIA-1 cytolytic cells outside (periphery of the follicle and interfollicular areas) than within the neoplastic follicle in follicular lymphomas (p<0.001). In small lymphocytic lymphomas, cytolytic cells were mainly seen as uniformly scattered single cells, distributed throughout the tumor environment. In mantle cell and diffuse large B-cell lymphomas these were most often seen as small clusters and less frequently as singly scattered cells. Higher numbers of CD4 + than the CD8 + T cells were observed in most cases. Contrary to the follicles in follicular hyperplasia, CD57 + NK cells were predominantly observed outside the neoplastic follicle in follicular lymphomas (FLs). These results outline specific interactions between the potential anti-tumoral cytolytic and the malignant cells of B-cell NHLs.