PAX-5

The PAX proteins are important regulators in early development, and alterations in the expression of their genes are thought to contribute to neoplastic transformation. The PAX-5 gene encodes the B-cell lineagespecific activator protein (BSAP) that is expressed at early, but not late, stages of B-cell differentiation. Its expression has also been detected in developing CNS and testis; therefore, PAX-5 gene product may not only play an important role in B-cell differentiation, but also in neural development and spermatogenesis.

PAX-5 expression is not only continuously required for B-cell lineage commitment during early B-cell development but also for B-cell lineage maintenance. PAX-5 is found in most cases of mature and precursor B-cell Non-Hodgkin’s Lymphomas/Leukemias. PAX-5 is not detected in Multiple Myeloma and solitary Plasmacytoma, making it useful for such differentiation. Diffuse Large B-cell Lymphomas do express PAX-5, except for those with terminal B-cell differentiation. T-cell neoplasms do not stain with anti-PAX-5; however, there is a strong association with CD20 expression.

PAX-5 is a rabbit monoclonal antibody derived from cell culture supernatant that is concentrated, dialyzed, filter sterilized and diluted in buffer pH 7.5, containing BSA and sodium azide as a preservative.

1. Torlakovic E, et al. Am J Surg Pathol. 2002;Oct;26(10):1343-50
2. Willenbrock K, et al. Lab Invest. 2002;Sep;82(9):1103-9
3. Falini B, et al. Blood. 2002;Jan15;99(2):409-26
4. Blood. 2003;Feb15;101(4):1505-12

1. Cut and mount 3-4 micron formalin-fixed paraffin-embedded tissues on positive charged slides.
2. Air dry for 2 hours at 58° C.
3. Deparaffinize, dehydrate and rehydrate tissues.
4. Subject tissues to heat epitope retrieval using a suitable retrieval solution such as ImmunoDNA Retriever with Citrate (BSB 0020-BSB 0023) or EDTA (BSB 0030-BSB 0033).
5. Any of three heating methods may be used:
   • Electric Pressure Cooker
     Place standoff rack at base of pressure cooker. Add 1-2 inches of distilled water to the pressure cooker and turn heat to high, and incubate for 15 minutes. Open and immediately transfer slides to room temperature.
   • Water Bath Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a water bath set at 95°-99° C. Incubate for 30-60 minutes.
   • Conventional Steamer Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a Steamer, cover and steam for 30-60 minutes.
6. After heat treatment, transfer slides in ImmunoDNA Retriever with Citrate or EDTA to room temperature and let stand for 15-20 minutes.
7. Wash slides with IHC wash buffer or DI water.
8. Continue IHC staining protocol.