Expression of cyclin D2 and D3 in lymphoid lesions

The D-type cyclins, involved in the regulation of G(1) progression of the c ell cycle, are expressed in a lineage-specific manner. Normal hematopoietic cells express cyclin D2 and/or D3. In order to determine whether their exp ression pattern changes in lymphoid tumors, we examined cyclin D2 and D3 ex pression in non-neoplastic and neoplastic lymphoid lesions, using a sensiti ve immunohistochemical amplification method. Centroblasts in lymphoid folli cles of reactive lymph nodes expressed exclusively cyclin D3 and no D2. Int erfollicular areas contained scattered cyclin D3 and D2 positive cells. By double staining, cyclin D3 was detected in CD79a positive B cells, CD3 posi tive T cells and CD68 positive macrophages. Cyclin D2 was present only in C D3 positive T cells. Neoplastic lymphoid lesions included 33 B cell lymphom as, 9 T cell lymphomas and 12 Hodgkin's lymphomas. The B cell lymphomas com prised 9 follicular lymphomas (FL), I Burkitt lymphoma (BL), 22 diffuse lar ge cell lymphomas (DL) and chronic lymphocytic leukemia (CLL). All 9 FLs an d the single BL expressed exclusively cyclin D3, similarly to germinal cent er B cells, that represent their cells of origin. Six DLs expressed both cy clin D2 and D3, while 6 expressed only D3. Among the 9 pleomorphic T cell l ymphomas, medium and large cell type, 5 expressed cyclin D2. Cyclin D3 was also detected in scattered cells in 4 of 9 cases and was highly expressed i n 2 of 9 T cell lymphomas. The majority of Hodgkin's lymphomas expressed bo th cyclin D2 and D3 in Hodgkin/Reed-Sternberg (HRS) cells. The high frequen cy of positive cells indicates that both cyclins were expressed in the same cells. (C) 1999 Wiley-Liss, Inc.