1112 - Immunophenotyping of Chronic Lymphocytic Leukemia in Yemen.

Background: Immunophenotyping is an essential component for the diagnosis of chronic lymphoproliferative disorders. This assessment is required by the WHO for disease classification and is a financial burden for resource-constrained countries. In Yemen there are also major logistical problems due to ongoing civil unrest.

Objectives: We aimed to establish and assess 3-color flow cytometry to assist in the diagnostic assessment of chronic lymphocytic disorders (CLL) in Yemen.

Methods: The immunophenotypic profile of 346 cases with the morphology of chronic lymphocytic leukemia that presented over a six years period was determined using a single laser FACSCalibur flow cytometer. CD45 / Side scatter gating was used to identify the leukemic cells. Antibodies used were to surface and intracellular antigens including CD45, CD34, CD10, CD19, CD20, CD79a, CD22, CD23, CD5, FMC7, CD11c, CD25, CD38, Kappa and Lambda. Antibodies were conjugated with FITC, PE or PerCP fluorophores.

Results: The patients aged in range from 22-90 (median 60) years, with a male: female ratio of 1.6:1 and the leucocyte counts 11-543x109/L. Flow cytometry was successful in all cases. CD19 was positive in all, along with other B-cell antigens CD20 (98%), CD79a (94%), CD23 (87%) with 75% of cases kappa and 25% lambda light chain restricted. CD5 was positive in 96% of cases, CD38 (52%), CD11c (43%), CD25 (89%) and FMC7 (34%). CD10 and CD34 were negative.

Conclusion: Despite the geopolitical conditions faced flow cytometry was able to be performed. The antigen expression patterns were in keeping with the WHO definition for CLL. However, there was higher expression of CD25 and CD11c, and half the cases in Yemen expressed CD38 antigen, known to be associated with a poorer prognosis.
Key Words: Flow cytometry, chronic lymphoproliferative disorders, Immuno-phenotyping.