The TCL1 gene, localized near the break point of chromosome 14q32.1 often i
nvolved in T cell leukemias, is also expressed in normal precursor T and B
cells, and B cell lymphoma cell lines. We investigated the expression of th
e TCL1 protein in various types of B cell lymphomas according to the Revise
d European-American Classification of Lymphoid neoplasms, Paraffin-embedded
tissue sections of lymphoma specimens were subjected to TCL1 immunohistoch
emistry, and positivity was scored on a three-tiered scale: - (< 25% cells)
, + (25-50% cells), and ++ (> 50% cells). The TCL1 protein was expressed in
low-grade B cell lymphomas including mucosa-associated lymphoid tissue typ
e in ocular adnexa (18/20, 90%), It was also expressed in follicular, lymph
oplasmacytic, and mantle cell lymphoma, but not in high-grade diffuse large
B cell lymphoma (2/11, 18%). These data suggest that the expression of the
TCL1 gene characterizes low-grade B cell lymphomas, and may be involved in
certain processes of lymphomatogenesis.