CD45 expression in low-grade B-cell non-Hodgkin's lymphomas

Area of Science:

• Hematology
• Immunology
• Oncology

Background:

• CD45 is a glycoprotein crucial for lymphohemopoietic cell function, with expression levels changing during B-lymphocyte development.
• Limited data exist on CD45 expression in diverse low-grade B-cell non-Hodgkin's lymphomas (NHL), with prior reports suggesting variable levels in chronic lymphocytic leukemia (CLL) and other NHLs.

Purpose of the Study:

• To investigate and delineate CD45 expression patterns across various subtypes of low-grade B-cell non-Hodgkin's lymphomas (NHL).
• To assess if CD45 expression can serve as a marker for B-lymphocyte maturation and aid in characterizing NHL subtypes.

Main Methods:

• Flow cytometry was used to evaluate CD45 expression in bone marrow samples from 107 NHL patients, including typical CLL, atypical CLL, mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), lymphoplasmacytic lymphoma (LPL), follicular lymphoma (FL), and hairy cell leukemia (HCL).
• Pathologic B-lymphocytes were identified using specific immunophenotypic markers (CD19/kappa or CD19/lambda).
• A CD45 index was calculated by normalizing the median fluorescence intensity (MFI) of pathologic B-lymphocytes to that of autologous T-lymphocytes to account for inter-sample variability.

Main Results:

• Four distinct CD45 expression patterns were identified: very low in typical CLL, relatively low in MCL, intermediate in MZL, LPL, and FL, and very high in HCL.
• Atypical cases, including one CD23-negative CLL, one CD23-positive MCL, and CLL with atypical morphology, exhibited very high CD45 expression.
• CD45 expression levels correlated with B-lymphocyte maturation stages across the studied NHL subtypes.

Conclusions:

• CD45 expression patterns differ significantly among low-grade NHL subtypes, reflecting varying B-lymphocyte maturation levels.
• The CD45 index provides a valuable tool for characterizing NHLs and may assist in distinguishing between subtypes and assessing disease characteristics.
• These findings contribute to a better understanding of B-cell lymphomagenesis and offer potential for improved diagnostic and prognostic stratification.