The Role of Kappa and Lambda in Subclassification of B Cell Lymphoblastic Leukemia in Sudanese Patients Using Flow Cytometry

Background: B-cell Acute lymphoblastic leukemia (B-ALL) is a neoplasm of lymphoblasts which are of B-cell lineage typically composed of small to medium sized blast cells, moderately condensed to dispersed chromatin with scanty cytoplasm and inconspicuous nucleoli, involving the bone marrow and/or blood. Methods and materials: This is a prospective cross-sectional study in which 50 blood and/or bone marrow samples of newly diagnosed patients (B-ALL) were tested for immunophenotyping. All samples were prepared for surface and cytoplasmic markers including kappa and lambda human antibody for 10 minutes in dark place and then run by the Flow Cytometer. Results: 64% of the study populations were males and 36% were females. Cases were classified according to immunophenotype and the age into different subtypes and showed the following frequencies: Pro B-ALL (8%), early pre B-ALL (56%), common B-ALL (16%), Pre-B-ALL (14%) and Mature B-ALL (only 6%). Surface immunoglobulin was positive in 10% and negative in 90% of all patients, showing 100% positivity in mature B-ALL and totally negative in other subtypes. While cytoplasmic immunoglobulin was positive in 16% and negative in 84% of all patients and was positive in 100% of Pre-B-ALL and in 50% of mature B-ALL. Surface kappa was more expressed in mature B-ALL than lambda giving a ratio of 2:1, while cytoplasmic kappa:lambda was 6:1 in Pre-B-ALL. Conclusion: Kappa and lambda have important role in B-ALL classification which necessitates their presence in immunophenotyping of B-ALL.