BOB.1

Synonyms: B cell specific Octamer Binding protein-1

by Jan Klos

Background

The protein is a transcriptional coactivator (a protein that controls the activity of transcription factors) encoded by POU2AF1 gene located on chromosome 11q23.1. It controls immunoglobulin genes and other genes critical for B-cell lineage identity. It seems also to be involved in formation of antigen-dependent germinal centers.

Staining in normal tissues

Positive staining often together with OCT2 is seen the cells of B-lineage expressing immunoglobulins and some activated T-cells while normal T-cells are negative.

Staining in tumors

Hodgkin/Reed-Sternberg cells in classical Hodgkin lymphoma (cHL) show downregulation of BOB.1 often together with OCT2 as a rule. EBV+ cases of cHL are more often positive than EBV negative cases. Staining for BOB.1 is as a rule positive in all cases of Nodular Lymphocytic Predominant Hodgkin Lymphoma (NLPHL). Positive staining is seen also in mature B-cell lymphomas, few T-cell lymphomas (ALCL and T-cell ALL) and some cases of Acute Myeloid Leukemia (including cases with t(15;17)(q22;q12), t(8;21)(q22;q22) and 11q23 abnormalities).

Staining pattern

Staining pattern is nuclear often with some weaker cytoplasmic reactivity.

Control tissue

Lymphoid tissue of tonsil.

Application

  • Used in panel together with OCT2 in differential diagnosis of classical Hodgkin lymphoma and NLPHL. Both markers (BOB.1 and OCT2) are positive in popcorn cells >90% of NLPHL cases confirming their full B-cell identity. Hodgkin/Reed-Sternberg cells in classical Hodgkin lymphoma show negative staining for one (20%) or more commonly (80%) for both markers supporting their B-cell origin.
  • May be also used for identification of B-cell lineage in panel with other antibodies, however PAX5 is more sensitive and more specific marker of B-cell lineage.

Selected references

  1. Abd El All HS: BOB-1 is expressed in classic Hodgkin lymphoma. Diagn Pathol 2007 Mar 8;2:1-10
  2. Gibson SE1, Dong HY, Advani AS, et al. Expression of the B cell-associated transcription factors PAX5, OCT-2, and BOB.1 in acute myeloid leukemia: associations with B-cell antigen expression and myelomonocytic maturation. Am J Clin Pathol. 2006 Dec;126(6):916-24.
  3. https://app.immunoquery.com/
  4. Loddenkemper C, Anagnostopoulos I, Hummell M et al: Differential Emu enhancer activity and expression of BOB.1/OBF.1, Oct 2, PU.1, and immunoglobulin in reactive B-cell populations, B-cell non-Hodgkin lymphomas and Hodgkin lymphomas. J Pathol 2004 Jan;202(1):60-69
  5. Marafioti T, Ascani S, Pulford K et al: Expression of B-lymphocyte-associated transcription factors in human T-cell neoplasms. Am J Pathol 2003 Mar;162(3):861-871
  6. McCune RC1, Syrbu SI, Vasef MA. Expression profiling of transcription factors Pax-5, Oct-1, Oct-2, BOB.1, and PU.1 in Hodgkin’s and non-Hodgkin’s lymphomas: a comparative study using high throughput tissue microarrays. Mod Pathol. 2006 Jul;19(7):1010-8. Epub 2006 Apr 28.
  7. Yin L1, Xu J2, Li M3, et al. Oct2 and Bob1 are sensitive and specific markers in lineage determination of B cell lymphomas with no expression of conventional B cell markers. Histopathology. 2016 Nov;69(5):775-783. doi: 10.1111/his.13017. Epub 2016 Aug 5.