CD34 is not Expressed by Blasts in a Third of B-ALL Patients and Its Negativity is associated with Aberrant Marker Expression: A Retrospective Analysis

BACKGROUND: CD34 antigen is expressed by early hematopoietic progenitor cells and acute leukemia cells. Its expression is associated with good prognosis in acute myeloid leukemia. Literature is sparse on its prognostic significance in B- acute lymphoblastic leukemia (B-ALL) especially from India. Hence the present study was undertaken to analyse the frequency of CD34 expression in B-ALL in Indian patients and determine its prognostic significance by associating with other prognostic markers and aberrant antigen expression. METHODS: Seventy-five B-ALL patients diagnosed by flow cytometry over a period of 3½ year were studied. Correlation of CD34 expression was studied with gender, age, total leucocyte count (TLC), French-American-British (FAB) morphological type, immuno-phenotypic markers, cytogenetics and minimal residual disease. Differences between groups were evaluated using Student’s T-test for quantitative data and Chi-square test/Fishers exact T-test for qualitative variables. P value <0.05 was considered significant. RESULTS: CD34 was positive in 66.66% (50/75) cases while it was negative in rest (33.33%; 25/75) cases. CD13, CD33, CD5, CD7 and CD11b were more frequently expressed in CD34 negative B-ALL (p=0.025). No association of CD34 expression was found with gender, age, TLC, FAB morphological type, other immune-phenotypic markers, MRD and cytogenetics studied. CONCLUSIONS: The expression of CD34 does not associate with known prognostic markers in B-ALL. However, absence of CD34 is associated with aberrant immunophenotypic expression (myeloid + T-cell antigens) in these patients. Larger studies with larger sample size and more extensive immunophenotypic panel needs to be done in Indian setup to confirm these findings.