p53 protein over‐expression and p53 gene abnormalities in HIV‐1‐related non‐Hodgkin's lymphomas

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Abstract
Alteration of the p53 tumor‐suppressor gene was studied in non‐Hodgkin's lymphomas (NHLs) from HIV‐I‐infected patients. p53 protein was over‐expressed in 10 out of the 45 (22%) cases analyzed, mainly clustering in the small‐non‐cleaved‐cell (SNC) (5/19) and Ki‐l+ anaplastic large‐cell (ALC) (3/8) subtypes, according to previous findings on HIV‐1 ‐unrelated NHLs. p53‐positive small‐non‐cleaved‐cell lymphomas presented a diffuse or clustered pattern of p53‐positive neoplastic cells consequent upon p53‐gene mutations. In contrast, in Ki‐1 + ALC lymphomas p53 immunohistochemical reactivity was limited to scattered tumor cells, and no p53‐gene alterations could be detected. These results suggest that p53‐gene alterations play a role in the lymphomagenetic process of a fraction of HIV‐I‐related SNC NHLs, however with a frequency no different from that observed in HIV‐I ‐unrelated NHLs of the same sub‐type. In HIV‐I‐related Ki‐I+ ALC lymphomas, mechanisms different from gene alterations might be implicated in over‐expression of p53 protein.