Immunohistochemical Analysis of Thymidine Phosphorylase Overexpression in Malignant Lymphomas (ML), Especially in Adult T-cell Leukemia/Lymphoma (ATLL)

In order to see whether Thymidine phosphorylase (TP)-positive lymphomas exist and whether there is relation between overexpression of TP and HTLV-1 infection, overexpression of TP/Platelet-derived endothelial cell growth factor (PD-ECGF) was examined in 59 cases of malignant lymphomas (ML) by means of Elite avidin-biotin complex method employing anti-TP monoclonal antibody. The 59 cases of ML comprised 20 nodal peripheral T-cell lymphomas (npT-ML), 10 extranodal peripheral T-cell lymphomas (epT-ML)，18 B-cell lymphomas (B-ML)，10 Hodgkin's diseases (HD), and one true histiocytic lymphoma. Fifteen cases of peripheral T-ceII lymphoma (pT-ML) including TP-positive cases, which were mentioned below, were examined in a point of HTLV-1 proviral DNA integration by means of polymerase chain reaction (PCR) and in a point of expression of HTLV-1 Tax preotein by means of modified ImmunoMax employing anti-HTLV-1 Tax monoclonal antibody， WATM-1. Only in three cases of epT-ML, TP-positive lymphoma cells were recognized. The three TP-positive epT-MLs were of ATLL expressing HTLV-1 Tax, as the most cases of ATLL did. Considering long survival time and smoldering clinical course in spite of high grade histology, two cases of the TP-positive ATLL in the skin might be of an unique clinical entity of ATLL and suggested that overexpression of TP in ATLL was a favorable feature. In the MLs other than the TP-positive ATLL, TP-positive cells were dominantly dendritic cells (DC) including lymphoid dendritic cells (LDC), Langerhans cells (LC), veiled cell (VC) and interdigitating dendritic cells (IDC). It was not clear that follicular dendritic cells (FDC) were positive for TP, although one case of B-ML associated many TP-positive dendritic cells. TP-positive LDCs were seen dominantly in T-zone lymphoma, B-MLs and in HD lymphocytic predominance. TP-positive IDCs forming mesh-like reticular work were noted in AILD type, pleomorphic type and anaplastic large cell type of pT-ML and HD mixed cellularity and lymphocytic depletion. In three cases of B-ML increase of spindle cells revealing nuclear stain of TP was noted. Epithelioid cells in T-cell lymphoepithelioid cell lymphoma and in MATL type B-cell lymphoma were positive for TP. Only in one case of 10 AILD type npT-ML endothelial cells were positive for TP. Most DCs and epithelioid cells were labeled by TP so that TP may be a lineage marker of T-cell associated DC. On the other hand, the cytoplasmic TP in IDC forming mesh-like reticular work in AILD type, high-grade pT-MLs and HD would be induced under cytokines from lymphoma cells and suggested TP's effects on developing processes of IDC