Surface markers in non-phagocytic hairy cell leukemia

Area of Science:

• Hematology
• Immunology
• Cell Biology

Background:

• Hairy cell leukemia (HCL) is a rare B-cell malignancy.
• Characterizing the surface markers and functional properties of HCL cells is crucial for understanding their origin and behavior.

Observation:

• Phase contrast and scanning electron microscopy confirmed the presence of hairy cells in peripheral blood, bone marrow, and spleen.
• Immunofluorescence revealed high expression of IgD (92%) and albumin (95%) on spleen cells, with significant IgG (76%) and minimal IgM (12%).

Findings:

• Surface marker expression shifted after culture, with IgD and IgM persisting while IgG and albumin decreased.
• Hairy cells demonstrated Fc receptor activity, forming rosettes with IgG-coated erythrocytes (EA), which increased after enzymatic treatment.
• Cells did not form rosettes with complement-coated erythrocytes (EAC) or non-sensitized erythrocytes, nor did they exhibit phagocytic activity.

Implications:

• The observed surface markers and functional characteristics strongly suggest a B-lymphocyte origin for the hairy cells in this patient.
• Understanding these cellular properties aids in differentiating HCL from other lymphoid malignancies and informs potential therapeutic strategies.