Extra

CD19 expressed through most of b-cell development pan b-cell marker and may therefore be used to confirm b-lymphocyte lineage being present at early b-cell commitment until plasma cell stage.

normal expression and function

CD19 part of the normal b-cell receptor bcr complex of proteins and plays a major role in the recruiting and activating signalling proteins involved in b-cell receptor activation. it reliably expressed by most normal b lymphocytes and also by follicular dendritic cells. expression acquired very early during normal b-cell development and tends to increase as b cells mature but lost during the transition to antibody producing plasma cells.

diagnostic role

• CD19 very useful for confirming b-lineage for both normal and malignant b cells
• it important to recognise that expression may be absent in very early cases of all and that CD19 not present on plasma cells.
• the level of expression of CD19 varies. for example high levels in hairy cell leukaemia with relatively low levels of expression in cll
• expression may be absent in cases of diffuse large b-cell lymphoma
• expression a fairly common aberrant feature in aml particularly cases with the t 8;21 cytogenetic lesion but expression rare in other lineages.

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1. expression by acute leukaemias and by haematogones 

file freqepng pro-b all link flow cytometry key file hiepng early pre-b all link flow cytometry key file hiepng pre-b all link flow cytometry key file hiepng early b all link flow cytometry key file rareepng pro-t all link flow cytometry key file rareepng mature-t all link flow cytometry key file possepng aml * link flow cytometry key file hiepng haemato-gones link flow cytometry key

• particularly seen in aml with t 8 21 translocation

2. expression by b-lymphoproliferative disorders file hi.png frame cll * link flow cytometry key file hiepng pll** link flow cytometry key file hiepng mcl link flow cytometry key file hiepng fl * link flow cytometry key file hiepng hcl** link flow cytometry key file hiepng hclv link flow cytometry key file hiepng mzl link flow cytometry key file hiepng lpl link flow cytometry key file possepng pcs link flow cytometry key * typically weak ** typically strong ----

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