Utility of CD200 expression and CD20 antibody binding capacity in differentiating chronic lymphocytic leukemia from other chronic lymphoproliferative disorders

Background: Chronic lymphoproliferative disorders (CLPDs) are heterogeneous group of disorders with variable clinical presentations and outcomes. Therefore, accurate classification is crucial for treatment planning. At present, flow cytometry immunophenotyping (FCM-IPT) is a useful tool for diagnosing these diseases. However, overlapping immunophenotypes do exist. Recently, differential expression of CD200 and variation in number of CD20 antibody bound per cell (ABC) in different CLPDs has been reported. Materials and Methods: Seventy-seven CLPD cases were analyzed by FCM-IPT for CD200 expression, and Quantibrite bead was used to calculate CD20 ABC. Results: Variability in CD200 expression can help in the differentiation of chronic lymphocytic leukemia (CLL) and hairy cell leukemia (HCL) from other CLPDs. CD200 was brightly expressed in 100% CLL cases, having homogenous bright (2+) intensity. On the contrary, CD200 was uniformly negative in all Mantle cell lymphoma cases except 1, in which the intensity was dim, and the mean fluorescence intensity was significantly lower than CLL. Furthermore, all HCL cases showed bright expression of CD200, thereby making it useful in differentiation from other CLPD with villous lymphocytes. Evaluation of CD20 ABC showed that it differs among various CLPD and was significantly lowest in CLL and highest in HCL both on peripheral blood and bone marrow samples. Conclusion: Our results support the fact that CD200 can be added to routine CLPD panel as it is useful in subcategorizing them. However, inclusion of CD20 ABC to routine panel does not seem plausible but may be done for difficult diagnostic cases or where anti-CD20 therapy is planned.

Comparative Quantitative Analysis of Cluster of Differentiation 45 Antigen Expression on Lymphocyte Subsets / 대한진단검사의학회지

BACKGROUND: Since the recent introduction of radioimmunotherapy (RIT) using antibodies against cluster of differentiation (CD) 45 for the treatment of lymphoma, the clinical significance of the CD45 antigen has been increasing steadily. Here, we analyzed CD45 expression on lymphocyte subsets using flow cytometry in order to predict the susceptibility of normal lymphocytes to RIT. METHODS: Peripheral blood specimens were collected from 14 healthy individuals aged 25-54 yr. The mean fluorescence intensity (MFI) of the cell surface antigens was measured using a FACSCanto II system (Becton Dickinson Bioscience, USA). MFI values were converted into antibody binding capacity values using a Quantum Simply Cellular microbead kit (Bangs Laboratories, Inc., USA). RESULTS: Among the lymphocyte subsets, the expression of CD45 was the highest (725,368+/-42,763) on natural killer T (NKT) cells, 674,030+/-48,187 on cytotoxic/suppressor T cells, 588,750+/-48,090 on natural killer (NK) cells, 580,211+/-29,168 on helper T (Th) cells, and 499,436+/-21,737 on B cells. The Th cells and NK cells expressed a similar level of CD45 (P=0.502). Forward scatter was the highest in NKT cells (P<0.05), whereas side scatter differed significantly between each of the lymphocyte subsets (P<0.05). CD3 expression was highest in the Th and NKT cells. CONCLUSIONS: NKT cells express the highest levels of CD45 antigen. Therefore, this lymphocyte subset would be most profoundly affected by RIT or pretargeted RIT. The monitoring of this lymphocyte subset during and after RIT should prove helpful.

Comparative Quantitative Analysis of Cluster of Differentiation 45 Antigen Expression on Lymphocyte Subsets / 대한진단검사의학회지

BACKGROUND: Since the recent introduction of radioimmunotherapy (RIT) using antibodies against cluster of differentiation (CD) 45 for the treatment of lymphoma, the clinical significance of the CD45 antigen has been increasing steadily. Here, we analyzed CD45 expression on lymphocyte subsets using flow cytometry in order to predict the susceptibility of normal lymphocytes to RIT. METHODS: Peripheral blood specimens were collected from 14 healthy individuals aged 25-54 yr. The mean fluorescence intensity (MFI) of the cell surface antigens was measured using a FACSCanto II system (Becton Dickinson Bioscience, USA). MFI values were converted into antibody binding capacity values using a Quantum Simply Cellular microbead kit (Bangs Laboratories, Inc., USA). RESULTS: Among the lymphocyte subsets, the expression of CD45 was the highest (725,368+/-42,763) on natural killer T (NKT) cells, 674,030+/-48,187 on cytotoxic/suppressor T cells, 588,750+/-48,090 on natural killer (NK) cells, 580,211+/-29,168 on helper T (Th) cells, and 499,436+/-21,737 on B cells. The Th cells and NK cells expressed a similar level of CD45 (P=0.502). Forward scatter was the highest in NKT cells (P<0.05), whereas side scatter differed significantly between each of the lymphocyte subsets (P<0.05). CD3 expression was highest in the Th and NKT cells. CONCLUSIONS: NKT cells express the highest levels of CD45 antigen. Therefore, this lymphocyte subset would be most profoundly affected by RIT or pretargeted RIT. The monitoring of this lymphocyte subset during and after RIT should prove helpful.