Changing clinical, morphological and immunological patterns in chronic lymphocytic leukaemia

Area of Science:

• Hematology
• Immunology
• Oncology

Background:

• Chronic lymphocytic leukemia (CLL) is a common B-cell malignancy characterized by the accumulation of morphologically normal small lymphocytes.
• Understanding the immunophenotypic evolution of CLL is crucial for diagnosis and treatment.

Observation:

• Two cases of CLL exhibited a terminal phase where abnormal lymphocytes, resembling those in lymphosarcoma cell leukemia, replaced normal lymphocytes.
• This morphological shift was accompanied by significant changes in surface immunoglobulin (Ig) markers on the malignant cells.

Findings:

• Initially, the majority of lymphocytes expressed IgM. As the disease progressed and abnormal cells increased, these were replaced by cells expressing IgG.
• In one case, anti-delta antiserum revealed a substantial population of IgD-bearing lymphocytes, indicating that over half the cells expressed both IgD and IgG surface markers.

Implications:

• The switch from IgM to IgG and the co-expression of IgD and IgG suggest a complex B-cell differentiation or aberrant maturation pathway in advanced CLL.
• These immunophenotypic changes may have prognostic significance and could inform therapeutic strategies targeting specific B-cell populations in refractory CLL.