Decrease of memory T helper cells (CD4+ CD45R0+) in hairy cell leukemia
F A van der Horst1, A van der Marel, G J den Ottolander
1Department of Hematology, University Hospital Leiden, The Netherlands.
Insights
Hairy cell leukemia (HCL) patients show reduced CD4+ T cells expressing CD45R0, indicating impaired T-cell function and potential susceptibility to infections. This contrasts with other B-cell leukemias.
Area of Science:
- Immunology
- Hematology
- Oncology
Background:
- Hairy cell leukemia (HCL) patients frequently experience opportunistic infections.
- This suggests a potential impairment in T-cell functioning within HCL patients.
- Understanding T-cell dynamics is crucial for managing HCL complications.
Purpose of the Study:
- To investigate T-cell functioning in HCL by analyzing naive and memory T-cell populations.
- To determine the expression of CD45R0 on CD4+ and CD8+ T cells in HCL patients.
- To compare T-cell profiles in HCL with healthy subjects and other chronic B-cell leukemias.
Main Methods:
- Flow cytometry was used to measure CD45R0 expression on CD4+ and CD8+ T cells.
- Analysis included 23 HCL patients, 13 healthy subjects, and 13 patients with other chronic B-cell leukemias.
- T-cell subsets (naive/memory) were quantified based on CD45R0 expression.
Main Results:
- HCL patients with active disease had significantly lower percentages and absolute numbers of CD4+ CD45R0+ T cells compared to healthy controls.
- No significant differences in CD8+ T cells expressing CD45R0 were observed between HCL patients and controls.
- Patients with chronic lymphocytic leukemia or leukemic non-Hodgkin's lymphoma showed an elevation in CD45R0-expressing T cells.
Conclusions:
- HCL is associated with a reduction in memory CD4+ T cells (CD4+ CD45R0+), suggesting impaired T-cell immunity.
- The underlying mechanism for reduced CD45R0 expression in HCL CD4+ T cells requires further investigation.
- These findings contribute to understanding T-cell dysfunction in HCL and its link to infections.
Abstract:
Patients with hairy cell leukemia (HCL) are prone to opportunistic infections, which suggests an impaired T-cell functioning. To investigate a possible mechanism of such an impairment, we determined the numbers of naive and memory T cells by measuring the expression of CD45R0 on CD4+ and CD8+ T cells in 23 HCL patients. As control, 13 healthy subjects and 13 patients with other chronic B-cell leukemias were studied. In HCL patients with active disease, the percentage of CD4+ CD45R0+ T cells was significantly lower compared to healthy subjects (41% versus 57%, p = 0.01). Also the absolute numbers of CD4+ CD45R0+ T cells were reduced (396 x 10(6)/l versus 615 x 10(6)/l, p = 0.02) compared to healthy subjects, whereas within the CD8+ subset no differences were found. A contrasting elevation of percentages and numbers of CD45R0-expressing T cells (p < 0.0001) was seen in patients with chronic lymphocytic leukemia or leukemic non-Hodgkin's lymphoma. No relationship between CD4+ CD45R0+ and splenectomy, treatment with alpha-interferon or monocyte numbers was found in the HCL population. Despite the fact that the underlying mechanism of the reduced expression of CD45R0 in CD4+ T cells remains unclear, our observations may contribute to the understanding of an impaired T-cell functioning in HCL.
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