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Updated: Apr 1, 2026
From a 2DE-Gel Spot to Protein Function: Lesson Learned From HS1 in Chronic Lymphocytic Leukemia
Published on: October 19, 2014
A CD21 low phenotype, with no evidence of autoantibodies to complement proteins, is consistent with a poor prognosis
Eva-Maria Nichols1, Rachel Jones1, Rachael Watson1
1Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, UK.
Insights
Reduced CD21 expression on B-cell chronic lymphocytic leukemia (CLL) cells is linked to poorer prognosis and impaired B-cell receptor signaling. This finding highlights CD21
Area of Science:
- Immunology
- Hematology
- Oncology
Background:
- B-cell chronic lymphocytic leukemia (CLL) involves altered B-cell receptor (BCR) signaling and autoimmune issues.
- Complement system protein CD21, interacting with the BCR, influences B-cell function.
Purpose of the Study:
- To investigate the role of CD21 in CLL pathogenesis and its association with clinical outcomes.
- To examine CD21 expression levels in CLL patients and correlate them with disease characteristics and survival.
Main Methods:
- Analyzed CD21 expression on B-cells from 106 CLL patients and 50 controls.
- Measured soluble CD21 and autoantibodies in patient serum.
- Correlated CD21 levels with IGHV mutation status, CD38, ZAP70, phosphotyrosine levels, and overall survival.
Main Results:
- CLL B-cells exhibited significantly lower CD21 expression compared to controls.
- Low CD21 expression correlated with unmutated IGHV, high CD38, and high ZAP70.
- Reduced CD21 expression was associated with impaired BCR signaling and predicted poorer overall survival.
Conclusions:
- Reduced CD21 expression on CLL B-cells is functionally relevant and linked to adverse clinical outcomes.
- CD21 may serve as a prognostic biomarker in CLL.
- Further research into CD21's role in CLL pathogenesis is warranted.
Abstract:
B-cell chronic lymphocytic leukemia (CLL) is characterized by differential BCR signaling and autoimmune complications. Complement modulates B-cell function via C3d and CD21 cross-linked to the B-cell receptor (BCR). We hypothesized that CD21 contributes to BCR signaling and participates in the autoimmunity associated with CLL. We analyzed CD21 expression on 106 CLL patient samples and matched serum from 50 patients for the presence of soluble CD21 and autoantibodies to CR2, CR1, MCP and FH. CD21 expression on CLL B-cells was significantly lower than that expressed on B-cells from age-matched controls (P < 0.0001) and was inversely correlated with soluble CD21 (r2 = -0.41). We found no evidence of autoantibody to any complement regulator. Low CD21 expression correlated to prognostic subsets of CLL patients, i.e. cases with unmutated IGHV genes (P = 0.0006), high CD38 (P = 0.02) and high ZAP70 expression (P = 0.0017). Low CD21 expression was inversely correlated to the levels of phosphotyrosine induced in CLL cells following BCR ligation with αIgM (r2 = -0.21). Importantly, lower CD21 expression was also predictive for reduced overall survival (P = 0.005; HR = 2.7). In conclusion, we showed that reduced expression of CD21 on CLL B-cells appears functionally relevant and was associated with poor clinical outcomes.
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