Which marker is a B-cell transcription factor used as a marker in immunophenotyping?

Which marker is a B-cell transcription factor used as a marker in immunophenotyping?

• A. CD20
• B. Pax-5
• C. CD3
• D. CD56

Answer: (B)

This item tests recognizing a B-cell transcription factor used in immunophenotyping. Pax-5, also known as BSAP, is a nuclear transcription factor essential for B-cell development and maintenance. Because it resides in the nucleus, Pax-5 staining helps identify B-cell lineage even when surface markers are variable or downregulated, making it a reliable companion marker in immunophenotyping of lymphomas and other B-cell neoplasms. It is detectable as a nuclear stain, in contrast to surface markers like CD20, CD3, or CD56, which appear on the cell membrane. The other options are surface markers for different lineages (CD20 for mature B cells, CD3 for T cells, CD56 for NK cells), not transcription factors. Hence, Pax-5 is the B-cell transcription factor used as a marker in immunophenotyping.

This item tests recognizing a B-cell transcription factor used in immunophenotyping. Pax-5, also known as BSAP, is a nuclear transcription factor essential for B-cell development and maintenance. Because it resides in the nucleus, Pax-5 staining helps identify B-cell lineage even when surface markers are variable or downregulated, making it a reliable companion marker in immunophenotyping of lymphomas and other B-cell neoplasms. It is detectable as a nuclear stain, in contrast to surface markers like CD20, CD3, or CD56, which appear on the cell membrane. The other options are surface markers for different lineages (CD20 for mature B cells, CD3 for T cells, CD56 for NK cells), not transcription factors. Hence, Pax-5 is the B-cell transcription factor used as a marker in immunophenotyping.