Background: Leukemic cells express a characteristic set of "cluster of differentiation" (CD) markers, which forms the basis of the current WHO classification. Leukemia-associated aberrant immunophenotype (LAIP) refers to expression of unusual CD markers by leukemic cells, which are not normally expressed by their respective lineage. The incidence of LAIP varies considerably, and its clinical implications, prognostic relevance, and sensitivity to therapy are still debatable. This study was conducted to identify the immunophenotypic aberrancies in newly diagnosed leukemias in our Institute.
Method: This was an observational study, which included newly diagnosed leukemias on flow cytometry. Aberrant immunophenotypic expressions were recorded whenever present and were correlated with prognostic factors like age, gender, and total leucocyte count (TLC).
Results: The study included 110 newly diagnosed cases of leukemias (85 acute and 25 chronic) over 1.5 years. Immunophenotypic aberrancies were detected in 40.4% of the cases. The highest incidence of aberrations was detected in acute myeloid leukemia (60.7%). LAIPs were detected in 50% of T-acute lymphoblastic leukemia and 25% cases of in B-cell acute lymphoblastic leukemia (B-ALL). Aberrant CD33 and CD56 expression in B-ALL correlated with poor prognostic factors like higher age and higher TLC, respectively. Immunophenotypic aberrancies were present in 28% cases of chronic lymphocytic leukemia.
Conclusion: The results of this study have generated valuable baseline data on the incidence of LAIPs in this region. This information is vital because establishing LAIPs at the time of diagnosis is crucial for disease monitoring. Some LAIPs are associated with underlying cytogenetic abnormalities and hence impact the management and prognosis.
Keywords: Aberrant antigen expression; acute leukemia; chronic leukemia; cluster of differentiation; flow cytometry; immunophenotyping.