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Revision as of 21:27, 17 May 2023

CD79a

pan-b cell marker that has high degree of specificity for the identification of b-lineage. CD79a is expressed initially in cytoplasm before appearing on the membrane as surface heavy chain expression is acquired.

normal expression and function CD79a associates with CD79b and the immunoglobulin chains of the b-cell receptor. together these chains mediate the signalling of the b-cell receptor however each is expressed slightly differently - CD79a is more reliable lineage-specific marker than CD79b which may have more variable expression. expression is acquired during early b-lymphocyte formation - initially in cytoplasm before appearing on the membrane of more mature cells and persisting until plasma cell differentiation.

diagnostic role

reliable marker of b-lymphocyte lineage with relatively low levels of aberrant expression
CD79a should be considered more specific than CD19 or CD20 although it may rarely be expressed on other cell types.
in all expression in cytoplasm is acquired at an early stage of b-lineage commitment pro-b differentiation
expression is on the cell surface at later differentiation as surface heavy chains are acquired.
in myeloma about half of cases will express this marker strongly with further proportion having weak expression.

other relevant information CD79a expression is recognised on some aml and t-all cases so caution should be exercised particularly where other features are atypical. like CD19 expression of CD79a is more often associated with aml that has t 8;21 translocation though less common .

summary tables 1. expression by acute leukaemias and by haematogones file freq pro-b all hi early pre-b all hi pre-b all hi early b all rare pro-t all rare mature-t all poss aml hi haemato-gones link flow cytometry key CD79a cytoplasmic together with CD19 and CD22 can be used in to indicate b-lineage in pro-all and remains cytoplasmic until the b-all stage 2. expression by b-lymphoproliferative disorders file hi frame cll * hi pll** hi mcl hi fl * hi hcl** hi hclv hi mzl hi lpl freq pcs

@@ Line 1: / Line 1: @@
-CD34
+CD79a
-*Often regarded as a marker of primitive phenotype, CD34 is expressed by many cases of ALL (around 50%) and slightly fewer cases of AML around (40%)
+pan-b cell marker that has  high degree of specificity for the identification of b-lineage. CD79a is expressed initially in cytoplasm before appearing on the membrane as surface heavy chain expression is acquired.
-*CD34 is also expressed by regenerating cells in marrow, and particularly by regenerating B lymphocytes (haematogones)
-what is its normal function and expression
+normal expression and function
-CD34 is a membrane protein that is likely to play a role in the retention of cells within the stem cell niche where it may also contribute to their subsequent maturation. CD34 is acquired at the stage of pluripotent stem cells and is retained by committed stem cells before being lost as the cells mature. CD34 is also expressed by mast cells and by some non-haematopoietic cells particularly endothelial cells.
+CD79a associates with CD79b and the immunoglobulin chains of the b-cell receptor. together these chains mediate the signalling of the b-cell receptor however each is expressed slightly differently - CD79a is  more reliable lineage-specific marker than CD79b which may have more variable expression. expression is acquired during early b-lymphocyte formation - initially in cytoplasm before appearing on the membrane of more mature cells and persisting until plasma cell differentiation.
-what is its diagnostic role
+diagnostic role
-*CD34 is commonly used to identify the primitive nature of early lymphoid or myeloid cells i.e. blast cells of ALL and AML
+* reliable marker of b-lymphocyte lineage with relatively low levels of aberrant expression
-*Rare very primitive cases of acute leukaemia may be identified solely through their expression of CD34 and CD45
+*CD79a should be considered more specific than CD19 or CD20 although it may rarely be expressed on other cell types.
-*CD45 is also expressed by regenerating cells in marrow and also by regenerating haematogones so caution is necessary in interpretation in regenerating marrows
+*in all expression in cytoplasm is acquired at an early stage of b-lineage commitment pro-b differentiation
+*expression is on the cell surface at later differentiation as surface heavy chains are acquired.
+*in myeloma about half of cases will express this marker strongly with further proportion having weak expression.
 other relevant information
-Histopathologists often use CD34 to demonstrate the number of primitive cells in bone marrow trephine biopsies e.g. in the assessment of primitive cell number in myelodysplaia; however a range of other cell types in bone marrow also express CD34 in marrow, and these include vascular endothelial cells and mast cells.
+CD79a expression is recognised on some aml and t-all cases so caution should be exercised particularly where other features are atypical. like CD19 expression of CD79a is more often associated with aml that has t 8;21 translocation though less common .
-----  summary tables
+----  summary tables  1. expression by acute leukaemias and by haematogones file freq  pro-b all   hi  early pre-b all   hi  pre-b all   hi  early b all   rare  pro-t all   rare  mature-t all   poss  aml   hi  haemato-gones  link flow cytometry key CD79a cytoplasmic together with CD19 and CD22 can be used in to indicate b-lineage in pro-all and remains cytoplasmic until the b-all stage 2. expression by b-lymphoproliferative disorders file hi frame  cll *  hi  pll**   hi  mcl   hi  fl  *  hi  hcl**   hi  hclv   hi  mzl   hi  lpl   freq  pcs
-. expression by acute leukaemias and by haematogones
-freq  pro-b all
-freq  early pre-b all
-freq  pre-b all
-poss  b all
-freq  pro-t all
-freq  mature-t all
-freq  aml
-hi  haemato-gones
-* in aml expression is rare in apl and is less frequent in npm1-mutated patients, Burkitt
-. expression by b-lymphoproliferative disorders
-rare cll
-rare  pll
-rare  mcl
-rare  fl link
-rare  hcl
-rare  hclv
-rare  mzl
-rare  lpl
-rare  pcs

Extra: Difference between revisions

From haematologyetc.co.uk

Revision as of 21:27, 17 May 2023