Anti-CD5 monoclonal antibody, clone DWT6

BackgroundThe data on the clinical utility of the quantitative assessment of immunophenotypes in distinguishing mature CD5-positive B-cell neoplasms is limited. The study aim was to assess the diagnostic value of the quantitative assessment of a panel of 18 markers and to identify the most informative ones. MethodsThe immunophenotype of the neoplastic population was determined in diagnostic specimens from 188 patients. BD FACSCanto II flow cytometer and FACSDiva software were used to analyze the positivity/negativity and mean fluorescence intensity (MFI) of the surface expression of 18 markers. Advanced data mining methods were used to define the key differential diagnostic features of CLL/SLL (chronic lymphocytic leukemia/small lymphocytic lymphoma), MCL (mantle cell lymphoma), and CD5+ MZL (marginal zone lymphoma). ResultsThe most informative markers for the distinction of CLL/SLL, MCL, CD5+ MZL, including atypical cases, were the MFI values of CD79b, CD20, CD23, CD43, CD38, CD11c, FMC7, CD200, kappa light chain, and their combinations. CD23 and CD200 were the most discriminant between CLL/SLL and MCL and CD23 plus CD79b between CLL/SLL and CD5+ MZL. The quantitative analysis of the most informative markers failed to accurately distinguish MCL and CD5+ MZL. The study highlights the data mining methods for the analysis and selection of the most informative immunophenotypic markers and for the design of a predictive model (diagnostic classifier), minimizing the subjectivity of expert-based assessment. ConclusionsOur data confirmed that the quantification of the expression of informative markers increases the diagnostic value of immunophenotyping in mature CD5+ B-cell neoplasms. (c) 2017 International Clinical Cytometry Society

Monoclonal B-cell lymphocytosis (MBL) is defined by the presence of a monoclonal B-cell population in the peripheral blood (PB) at a concentration of < 5 x 10(9)/l and no signs or symptoms of a lymphoproliferative disorder. In around 75% of cases, the immunophenotype of the clonal B-cell expansions is superimposable to that of chronic lymphocytic leukemia (CLL), thus defined "CLL-like". Other cases may coexpress CD19, CD5, bright CD20, and lack CD23 ("atypical CLL"), while others are CD5-negative ("non-CLL"). Beside the immunophenotypic profile, a key distinction is based on the B-cell count, stratifying the MBL category in low (< 0.5x10(9)/l) or high-count (>= 0.5x10(9)/l). Low-count (LC) MBL is recognized in general population studies and it is not associated with lymphocytosis. High-count (HC) MBL is identified during the clinical work-up for lymphocytosis and carries a risk of progression to CLL requiring therapy of 1-2% per year in most series, warranting clinical monitoring over time. At the time of MBL diagnosis, the key point is the careful evaluation and exclusion of differential diagnoses. After the initial workup, the follow-up at a referral center by a hematologist would be desirable as, in addition to the obvious risk of progression to clinically relevant CLL, the appropriate management of MBL individuals should take into account the risk of developing infections, other cancers and autoimmune disorders. For those cases who indeed bear a risk, though limited, of clinical consequences, such as the majority of HC-MBL cases, current evidences suggest that they may benefit from a tailored and specialized approach.