PAX5

PAX5

A gene on chromosome 9p13, of which there are multiple isoforms, of which PAX-5A is most studied. It encodes 50-kD B-cell specific activator protein (BSAP), which is expressed in pre-B and mature B cells, but is downregulated/silenced during terminal differentiation of plasma cells under the influence of B-lymphocyte-induced maturation protein-1 (PRDM1). PAX-5A influences the expression of other B-cell specific genes, including CD19 and CD20 and CD79a, preceding the expression of CD20.
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The tumor cells were negative for anaplastic lymphoma kinase (ALK) protein, B-cell markers (BCL6 and CD20), T-cell markers (CD56, TIA-1, CD4, CD5, CD7, CD43), and HHV-8, PAX5, and CD10.
The immunohistochemistry staining results showed these cells to be CD30+ (strong and diffuse); CD15 and PAX5 were positive in a few of these cells.
Markers that were negative (0%) included CD30 (n = 6), [kappa] light chain (n = 2), [lambda] light chain (n = 2), CD8 (n = 2), CD1a (n = 1), CD2 (n = 1), CD5 (n = 1), CD7 (n = 1), CD15 (n = 1), CD45RO (n = 1), CDw75 (n = 1), CD79a (n = 1), CD123 (n = 1), CD138 (n = 1), PAX5 (n = 1), TCL-1 (n = 1), and anaplastic lymphoma kinase (ALK; n = 1).
In all study participants, one of the two copies of the PAX5 gene was
The inherited genetic mutation is located in a gene called PAX5, which is known to play a role in the development of some B cell cancers, including ALL.
In the hematopoietic system, recent work has shown that differentiation of lymphoid progenitor cells to a committed mature B-cell identity is dependent on the induction of the transcription factor PAX5 (41).
A panel of CD30, CD15, PAX5, CD20 and CD3 Immunostains along with in situ hybridisation (ISH) for EBV-encoded RNA (EBER) would usually suffice.
PAX5 is a nuclear stain which gives excellent staining and is very helpful in identifying B cells in Rituximab treated cases.
As BCL6 and PAX5 (master regulators of the germinal centre cell reaction and the B-cell transcriptional programmes, respectively) expression declines, the synthesis of other markers indicative of plasmacellular differentiation including multiple myeloma oncogene-1 (MUM1 or interferon regulatory Factor 4), VS38c, CD38 and CD138 (syndecan-1) increases [5], There is also a concomitant change from surface to cytoplasmic immunoglobulin expression, a reduction in CD45 (leukocyte common antigen or LCA) and CD20 expression in plasma cells.
Although positive for CD45, H/DS is negative for B-cell-specific antigens, including CD19, CD20, CD22, CD79a, and PAX5.