Related Experiment Video
Updated: Aug 8, 2026
The Use of Fluorescent Target Arrays for Assessment of T Cell Responses In vivo
Published on: June 19, 2014
CD25-negative hairy cell leukaemia: intracytoplasmic detection of Tac antigen and interferon-induced surface
Insights
Hairy cell leukaemia (HCL) can present without detectable CD25 on the cell surface. This study found interleukin-2 receptor (IL2R) or CD25 present in the cytoplasm of neoplastic cells in a CD25-negative HCL case.
Area of Science:
- Hematology
- Immunology
- Oncology
Background:
- Hairy cell leukaemia (HCL) is a B-cell chronic lymphoproliferative disorder.
- A characteristic immunophenotypic marker of HCL is strong expression of the interleukin-2 receptor (IL2R) p55 chain (CD25).
- CD25 negativity is rare in typical HCL cases, even when variant forms are excluded.
Observation:
- A case study of HCL with typical clinical, histological, and ultrastructural features was investigated.
- Immunophenotyping revealed a complete HCL marker profile, but lacked cell surface CD25 expression.
- Increased levels of soluble IL2R were detected in the patient's serum.
Findings:
- Cytospin analysis of neoplastic B cells demonstrated cytoplasmic CD25 (IL2R) expression.
- In vitro culture with interferon-alpha 2b induced detectable cell surface CD25 expression.
- These results indicate that cytoplasmic IL2R expression may account for CD25-negative HCL.
Implications:
- This finding suggests a potential mechanism for CD25-negative HCL, involving intracellular IL2R localization.
- The study highlights the importance of investigating intracellular antigen expression in immunophenotypic analysis.
- Understanding cytoplasmic IL2R expression could refine diagnostic criteria and therapeutic strategies for HCL.
Abstract:
Hairy cell leukaemia (HCL) is a chronic lymphoproliferative disease of B-cell lineage. One of the peculiar immunophenotypic markers is the strong expression of the p55 chain of the interleukin-2 receptor (IL2R), recognized by anti-CD25 (or anti-Tac) monoclonal antibody. However, it is known that in rare cases CD25 may not be detectable, even when variant forms of HCL are excluded. The possibility has not been investigated that in these situations CD25 is present in the cytoplasm of the neoplastic cells. This paper describes a case in which the clinical, histological, and electron microscopic features were consistent with a typical HCL. Immunophenotype analysis showed the whole spectrum of markers of HCL, except for the expression of IL2R. The soluble form of the molecule was, however, increased in the patient's serum. Cytospin staining of the neoplastic B cells with anti-CD25 clearly demonstrated the presence of IL2R in the cytoplasm of hairy cells. When the cells were cultivated in vitro in the presence of interferon-alpha 2b, CD25 was detectable at the membrane level. These findings suggest that at least some cases of CD25-negative HCL may express cytoplasmic IL2R.
