T cell receptor alpha expression in B-type chronic lymphocytic leukemia.

Area of Science:

• Immunology
• Hematology
• Molecular Biology

Background:

• Normal B lymphocytes typically express immunoglobulin genes but not T cell receptor (TCR) genes.
• Exceptions to this rule exist in some leukemic cells and cell lines, necessitating further investigation.
• B-cell chronic lymphocytic leukemia (B-CLL) is a lymphoid malignancy with potential for aberrant gene expression.

Purpose of the Study:

• To investigate the expression of T cell receptor (TCR) alpha and beta chain genes in B-cell chronic lymphocytic leukemia (B-CLL) samples.
• To determine if leukemic B cells in B-CLL can activate TCR gene expression.
• To characterize the nature of TCR gene expression in B-CLL.

Main Methods:

• In situ hybridization with fluorescein-labeled probes to detect TCR alpha and beta mRNA.
• Northern blot analysis to detect TCR alpha mRNA transcripts.
• Flow cytometry using anti-TCR alpha/beta monoclonal antibody WT31.
• Exclusion of T cell contamination by analyzing leukemic cell counts and CD2+ T lymphocyte percentages.

Main Results:

• TCR alpha mRNA was detected in 14 of 18 B-CLL samples.
• TCR beta mRNA was detected in 7 of 16 B-CLL samples.
• A truncated 1.4 kb TCR alpha mRNA transcript was identified in B-CLL samples.
• No significant cell surface expression of TCR alpha/beta was observed with WT31 antibody.

Conclusions:

• A significant proportion of B-CLL samples express a truncated TCR alpha mRNA.
• The TCR alpha gene can be activated in leukemic B cells arrested at a late differentiation stage.
• These findings highlight potential aberrant gene activation in B-CLL pathogenesis.