CD19

Summary

CD19 expressed through most stages of B-cell development and is considered a pan B-cell marker i.e. present at early B-cell commitment until plasma cell stage

Normal expression and function

CD19 forms part of the normal B-cell receptor, and plays a major role in the recruiting and activating signalling proteins involved in B-cell activation. it reliably expressed by most normal B lymphocytes and also by follicular dendritic cells. Expression is acquired very early during normal B-cell development and tends to increase as B cells mature before becoming lost during the transition to plasma cells.

Diagnostic role

• CD19 is very useful in the confirmation of B-lineage of normal and malignant b cells although not etirely specific
• Note however that expression may be absent in very early cases of all and that CD19 and is absent on plasma cells and in some cases of DLBCL
• The level of expression may be helpful with high levels in hairy cell leukaemia with relatively low levels of expression in CLL
• CD19 is a fairly common aberrant marker in AML particularly cases with the t 8;21 cytogenetic lesion

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SUMMARY TABLES

Note The colour and % refer to the proportion of cases expressing the marker. Additional comments on strength, or site of expression (if relevant) are given below the table. For full details of key click here. For further information about a particular disease state click <I> adjacent to the condition name

Expression in primitive cell types
AML	CMML	B ALL	Burkitt	T ALL	ETP ALL <I>	MPAL <I>	Hgns <I>
5-20%*	<5%	80-100%**	80-100%	<5%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%

Notes: xxxxx

Expression in mature B cell neoplasms
CLL	MCL	FL	MZL	HCL	DLBCL	LPL	PCL
? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%

Notes: xxxxx

Expression in mature T cell neoplasms*
ATLL	CTCL/Sezary	T-PLL	T-LGL	NK-LGL
? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%	? <5% 5-20% 20-40% 40-80% 80-100%

Notes: xxxxx

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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 ----