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Immunophenotypic and molecular genetic characterization of a case of CD8+ B cell chronic lymphocytic leukemia
V Attadia1, M Alosi, S Improta
1Department of Microbiology, Immunology and Virology, Udine University, Italy.
Insights
This study details a rare case of chronic B lymphocytic leukemia where B cells aberrantly expressed CD8 alpha/alpha homodimer. This unusual CD8 expression in B cells was linked to an abnormal CD8A gene configuration.
Area of Science:
- Hematology
- Immunology
- Molecular Biology
Background:
- Chronic B lymphocytic leukemia (B-CLL) is a mature B-cell neoplasm.
- Typically, B-CLL cells express B-cell markers like CD19, CD5, IgM, and IgD.
- Aberrant antigen expression can occur in B-CLL, but CD8 expression is rare.
Observation:
- A patient with stable chronic B lymphocytic leukemia presented with an unusual phenotype.
- Flow cytometry revealed CD19+, CD5+, IgM+, IgD+, lambda chain+ B cells.
- These B cells exhibited aberrant expression of CD8 alpha/alpha homodimer, with no CD8 beta staining.
Findings:
- Molecular analyses confirmed monoclonal immunoglobulin gene rearrangements, consistent with B-CLL.
- T cell receptor genes were in germline configuration.
- An abnormal configuration of the CD8A gene was identified specifically within the CD8+ B lymphocytic clone.
Implications:
- The findings suggest a potential link between CD8A gene configuration and aberrant CD8 expression in B-CLL.
- This case expands the understanding of immunophenotypic variations in B-CLL.
- Further research may elucidate the mechanisms driving CD8 gene dysregulation in lymphoid malignancies.
Abstract:
We report the case of a patient with chronic B lymphocytic leukemia, with stable clinical and hematological conditions in the absence of any treatment. The flow cytometry analysis of the patient's cells revealed a CD19+, CD5+, IgM+, IgD+, lambda chain-phenotype, along with an unusual expression of CD8 alpha/alpha homodimer. B cells did not stain with the anti CD8 beta monoclonal antibody T8/2T8 5H7. Molecular biology analyses confirmed the monoclonal rearrangements of immunoglobulin heavy and lambda light chain genes in the presence of a germline configuration of T cell receptor genes. Moreover, an abnormal configuration of the CD8A gene was found in the CD8+B lymphocytic clone. We suggest that the aberrant expression of the CD8 gene could be related to its abnormal configuration.