Extra

CD2

CD2 is a pan t-cell marker. In diagnostic use it may be less reliable than CD3 for identification of T-cell lineage, since loss of CD2 expression is seen in some peripheral T-cell lymphomas, and aberrant expression in AML is recognised (particularly the APL subtype).

normal expression and function

CD2 forms part of the T-cell receptor complex, mediating adhesion to accessory cells and assisting in the generation and control of intracellular signal transduction. Expression of CD2 is acquired during early T cell ontogeny, preceded by CD7 and cytoplasmic CD3 expression and is then retained through thymic maturation and by peripheral t cells. CD2 is also expressed only by a proportion of normal mast cells but is frequently expressed in systemic mastocytosis.

what is its diagnostic role

CD2 generally identifies T-cell lineage and is not expressed by normal B-cells

• In T-ALL and peripheral T-cell lymphomas CD2 may contribute to diagnosis, but loss of expression is recognised
• CD2 and CD7 are expressed by NK cells (in contrast to CD3) and may be used together with CD56 to identify NK cells
• In systemic mastocytosis CD2 (with or without CD25) is expressed on the abnormal mast cell population, and in a proportion of cases CD25 may provide greater sensitivity and specificity

summary tables

expression by acute leukaemias and by haematogones

file rar.png pro-b all key file rar.png early pre-b all key file rar.png pre-b all key file rar.png b all key file hiu82epng pro-t all key file hiu82epng mature-t all key file possu82epng aml * key file rar.png haemato-gones key

• recognised expression in aml particularly apml

expression by b-lyphoproliferative disorders

file modu82epng frame cll* key file rar.png pll key file rar.png mcl key file rar.png fl key file rar.png hcl key file rar.png hclv key file rar.png mzl key file rar.png lpl key file rar.png pcs

expression is recognised in most b-lpd but generally 5 of cases

• expression is recognised in cll overall around 20 of cases

expression by mature t-cell disorders file hiu82epng frame t-pll