Analysis of transcription factor OCT.1, OCT.2 and BOB.1 expression using tissue arrays in classical Hodgkin's lymphoma.

Hodgkin's lymphoma can be considered in most cases a B-cell lymphoma due to the presence of potentially functional immunoglobulin (Ig) gene rearrangements in the neoplastic cells. In contrast to lymphocyte-predominant Hodgkin's lymphoma, Hodgkin/Reed-Sternberg (HRS) cells from classical Hodgkin's lymphoma have low frequency of B-cell marker expression and lack Ig light and Ig heavy messenger RNA. Recent studies have shown transcription machinery deficiency in Hodgkin's lymphoma caused by an absence of the transcription factors OCT.1, OCT.2 and/or BOB.1. By using the tissue microarray technique, we have performed an immunohistochemical study of OCT.1, OCT.2 and BOB.1 in 325 classical Hodgkin's lymphoma cases. The results have been correlated with the expression of the B-cell markers CD20, CD79a, B-cell-specific activator protein (BSAP) and MUM.1, the presence of Epstein-Barr virus and the histological subtype. The percentage of CD20 and CD79a positivity was low (18 and 18%, respectively), whereas MUM.1 and BSAP were positive in the majority of cases. Considering the positive cases with independence of the intensity of staining, 62% of them expressed OCT.2, 59% OCT.1 and 37% BOB.1. Nevertheless, when we considered only the strongly positive cases, the results were similar to those previously described by others. No statistical association was found between the transcription factor expression, histological subtype and Epstein-Barr virus presence. To our knowledge, this is the largest series of classical Hodgkin's lymphoma cases in which the expression of transcription factors has been studied. We have found a notorious percentage of cases displaying weak positivity for OCT.2 and BOB.1 factors in HRS cells. We propose that other mechanisms different from the absence of transcription factors OCT.2 and BOB.1 might be involved in the control of Ig transcription and B lineage in classical Hodgkin's lymphoma.