Distinct CD81 expression profiles in chronic lymphocytic leukemia and acute lymphoblastic leukemia: an immunophenotyping study

Abstract Background B-lymphoproliferative disorders (B-LPDs) comprise a heterogeneous group of diseases characterized by uncontrolled production of lymphocytes that cause monoclonal lymphocytosis, lymphadenopathy, and bone marrow infiltration. They typically occur in people who have a compromised immune system with highly variable clinical course. cluster of differentiation (CD)81 Interacts directly with CD19 (via the second extracellular domain); this interaction is initiated early during biosynthesis in the endoplasmic reticulum/pre-Golgi compartments and is essential for trafficking and compartmentalization of CD19 receptor on the cell surface of activated B cells. CD19 associates directly with CD81, a member of the tetraspans family of proteins that includes CD9, CD37, CD53, CD63, and CD82. CD81 is expressed by most B lineage cells and by a wide variety of cell types including most lymphocytes, natural killer cells, both naive and memory CD4 positive T cells, eosinophils, neuroblastomas, fibroblasts, melanomas, and expressed in monocytes/macrophages at the protein level. Aim To study the expression pattern of CD81 in malignant B-LPDs. To study the diagnostic value of CD81 in malignant B-LPDs. To investigate the biological significance of CD81 expression in malignant B-LPDs. Participants and methods Case–control analytic study included 40 B-LPDs patients and 40 apparent normal patients (age and sex matched), who were tested for surface levels of CD81 by flow cytometry technique. Results The expression of the CD81 (presented as the percentage of cells expressing each molecule) was higher in B-LPDs as expected because lymphocytes have a proliferative capacity in contrast to the control group in which lymphocytes are mature and resting cells that do not proliferate. In this study, all cases of B-LPDs and the control group showed dim to moderate expression of CD81 in both heterogeneous and homogeneous patterns. There was a discrepancy between the expression of CD81 and the B cell-restricted CD19 denoting that CD81 is not a B cell-restricted gene. Blast cells showed dim CD81 expression, in contrast to hematogones that show the brightest CD81 expression. CD81 showed no wide expression difference between most cases in this study. It was observed that cases with high white blood cell at diagnosis showed high expression of CD81. Conclusion The decreased CD81 expression in leukemic cells in a high proportion of cases is a sensitive and specific marker for residual precursor B-acute lymphoblastic leukemia, CD81 showed no wide difference of expression between most of cases in this study. These results indicate that CD81 expression can be featured as a robust marker for leukemic blasts in cases of B-acute lymphoblastic leukemia and can be exploited as a valuable addition to flow cytometric monitoring of minimal residual disease. The addition of CD81 to the panel for chronic lymphocytic leukemia, it would be a useful diagnostic marker.