Rare adult acute lymphocytic leukemia with CD56 expression in the ECOG experience shows unexpected phenotypic and genotypic heterogeneity.
Expression of CD56, a marker of natural killer (NK) cells, in acute lymphocytic leukemia (ALL) is rare and, to date, has been described only in non-B lineage ALL. Among 194 patients with CD56 analysis on the ongoing Eastern Cooperative Oncology Group (ECOG) ALL trial, E2993, 6 cases of CD56+ ALL were found (3.1%) with a median of 95% of blast cells expressing CD56, compared with a median of 1% of blast cells in CD56- ALL (P = 0.0001). FAB-L2 characteristics dominated, without granulation. Blast cells from four CD56+ patients expressed T-cell antigens at variable levels of maturation. A clonal rearrangement of the T-cell receptor beta (TCRbeta) gene was detected only in one patient. TCRbeta variable gene usage studies in this and one other CD56+ ALL patient demonstrated a significantly perturbed usage pattern in both patients when compared with control lymphocytes. The two remaining cases typed as early pre-B ALL (CD19+, CD10+), with one case co-expressing CD7. Cytogenetically, 4 patients were normal, 1 complex abnormal, and 1 Philadelphia chromosome positive. Epstein-Barr virus (EBV) sequences were detected in one T- and both B-lymphoid cases. Our data suggest that CD56 is expressed at a precursor stage common to the T- and the B-cell lineage.
Paietta
E
E
Our Lady of Mercy Cancer Center, New York Medical College, Bronx, New York 10466, USA. epaietta@email.msn.com
Neuberg
D
D
Richards
S
S
Bennett
J M
JM
Han
L
L
Racevskis
J
J
Dewald
G
G
Rowe
J M
JM
Wiernik
P H
PH
D000328:Adult; D018941:Antigens, CD19 / Q000032:analysis; D019011:Antigens, CD7 / Q000032:analysis; D019002:CD56 Antigen / Q000032:analysis*; D004279:DNA, Viral / Q000032:analysis; D018572:Disease-Free Survival; D005260:Female; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D005838:Genotype; D004854:Herpesvirus 4, Human / Q000235:genetics; D006801:Humans; D016130:Immunophenotyping; D007621:Karyotyping; D007694:Killer Cells, Natural / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015260:Neprilysin / Q000032:analysis; D010641:Phenotype; D010677:Philadelphia Chromosome; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000276:immunology* / Q000473:pathology; D012074:Remission Induction
D018941:Antigens, CD19; D019011:Antigens, CD7; D019002:CD56 Antigen; D004279:DNA, Viral; D015260:Neprilysin