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CD33+ B-cell precursor acute lymphoblastic leukemia in children: a distinct subgroup of B-cell precursor acute
Insights
CD33 expression in childhood B-precursor acute lymphoblastic leukemia (ALL) is linked to specific cell markers and older age. While initially a poor prognostic indicator, its significance requires further investigation, especially in relapsed cases.
Area of Science:
- Pediatric Hematology
- Oncology
- Immunophenotyping
Background:
- B-precursor acute lymphoblastic leukemia (ALL) is a heterogeneous malignancy in children.
- CD33 expression is a marker investigated for its role in ALL prognosis and biology.
- Understanding antigen expression is crucial for refining ALL classification and treatment strategies.
Purpose of the Study:
- To analyze clinical and laboratory features associated with CD33 expression in pediatric B-precursor ALL.
- To investigate the role of CD33 expression at diagnosis and relapse.
- To explore the implications of CD33 expression on treatment resistance and disease outcome.
Main Methods:
- Immunophenotypic analysis of CD33 expression in 123 children with B-precursor ALL.
- Correlation of CD33 expression with clinical parameters (age, disease status: onset, relapse, refractory).
- Assessment of coexpression of other antigens (CD2, CD4, CD7) and survival data (event-free survival).
Main Results:
- CD33 expression was found in 15.3% of patients at onset and 36.8% at relapse/refractory states.
- CD33+ patients were older and showed coexpression of T-cell and multipotential hematopoietic antigens.
- Univariate analysis indicated CD33 as a predictor of poor outcome, but this was not significant in multivariate analysis.
Conclusions:
- CD33+ B-precursor ALL may originate from undifferentiated cells with limited B-cell commitment.
- Acquisition of CD33 expression during relapse suggests clonal evolution or expansion of resistant clones.
- Further research is needed to clarify the prognostic and therapeutic implications of CD33 in B-precursor ALL.
Abstract:
Clinical and laboratory features associated with CD33 expression were analysed in 123 children with B-precursor acute lymphoblastic leukemia (ALL), including 85 at onset, 34 at relapse and four in a refractory state to induction therapy. CD33 was demonstrated in 13 patients (15.3%) at onset, and it was associated with coexpression of T-cell and multipotential hematopoietic cell-associated antigens, i.e. CD2, CD4 and CD7, which were observed in four of 11 analysed patients (P < 0.01). Patients with CD33 expression were older than those without CD33 (P < 0.01). Although CD33 was the strongest predictor of a poor outcome (event-free survival, 44% for CD33+ and 75% for CD33-patients; P = 0.0041) in univariate analysis, multivariate analysis did not demonstrate significance (P = 0.0645). Fourteen of 38 patients (36.8%) at relapse or in a refractory state showed CD33 expression. Analysis of CD33 expression had also been performed at onset in 16 of these patients and showed acquisition of CD33 in six of 13 patients who had been negative for this antigen at onset. Thus, it seems that CD33+ B-precursor ALL is derived from undifferentiated cells minimally committed to B-cell lineage and more homogeneous than so-called My+ B-precursor ALL with regard to the clinical and biological features. The frequent expression of CD33 on the cells which acquired resistance to chemotherapy may have resulted from expansion of a CD33+ original minor clone or clonal evolution.