CD7 Positive Acute Myeloblastic Leukaemia: An Heterogeneous Leukaemic Subtype

Abstract

Eleven patients whose myeloblasts expressed the CD7 antigen were identified among 48 consecutive cases of AML (22.9%). Only one patient's blasts expressed other T-cell markers and clonal rearrangement of the T-cell receptor δ chain gene was identified in only one of seven cases examined. CD7 positive AML was heterogeneous with regard to FAB type, age and presenting peripheral blood white cell count. Eight patients (72.7%) were morphologically FAB Ml or M2, two (18.2%) M4 and one (9.1%) M5. Neither age nor presenting white blood cell count was significantly different between the CD7+ and CD7- AML's (CD7+ :median 64 years, range 15–84; CD7 - :median 58 years, range 15–85: CD7 + :median WCC 5.9 × 10⁹/1, range 1.5–328; CD7- :median 18.3, range 0.7–355). In contrast to a previous report, no association was seen between CD7+ AML and abnormalities of chromosome 5. There was a tendency to lower remission rates in patients with CD7+ AML. Only four of ten CD7+ patients (40%) who received full induction chemotherapy entered a complete remission, whereas 20 of 25 (80%) CD7- AML's achieved this (0.1 > p > 0.05).

Although CD7 expression alone did not reach statistical significance as a prognostic variable, combining CD7 with CD14 expression defined three subgroups showing different responses to induction chemotherapy. CD7 + CD14+ AML's all failed to achieve remission, whereas 83.3% of CD7- CD14- AML's achieved remission and leukaemias in which either CD7 or CD14 was expressed displayed an intermediate response to induction chemotherapy (p = 0.02).

Key Words:

• CD7
• AML
• TCR δ
• Rearrangement
• CD14