Octamer transcription factor-2 (OCT-2) possesses a leucine zipper domain and belongs to the POU family of transcription factors. It specifically binds to the octamer motif (5- ATTTCAT-3), activates immunoglobulin gene expression and regulates transcription in a number of tissues. OCT-2 is important for the expression of B cell specific genes, such as CD20 and CRISP-3. OCT-2 is expressed in mature B cells, predominantly germinal center B cells. Low expression of OCT-2 has been found in immature B cells, T cells and myelomonocytic cells. OCT-2 reactivity in epithelial cells and neuronal cells has also been reported. The OCT-2 antibody labels various B cell lymphomas with strong expression in germinal center-derived lymphomas. In a study on Hodgkin's lymphoma (HL), OCT-2 positivity has been observed in 15 out of 15 lymphocyte predominance HLs, but none of the 29 classic HLs.