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Distribution of C3-step regulatory proteins of the complement system, CD35 (CR1), CD46 (MCP), and CD55 (DAF), in
1Department of Immunology and Hematology, Center for Adult Diseases Osaka, Japan.
Insights
Complement regulators CD46 and CD55 show altered expression in leukemia cells, impacting hematological malignancies. CD35 is largely absent in leukemia, while CD46 is elevated and CD55 is often lost.
Area of Science:
- Immunology
- Hematology
- Cell Biology
Background:
- Complement regulatory proteins (CRPs) like CD35, CD46, and CD55 are crucial for immune homeostasis.
- Dysregulation of CRPs is implicated in various diseases, including hematological malignancies.
Purpose of the Study:
- To investigate the distribution and expression levels of CD35, CD46, and CD55 in normal and malignant blood cells.
- To explore the potential roles and clinical applications of these CRPs in hematological malignancies.
Main Methods:
- Analysis of CD35, CD46, and CD55 expression on peripheral blood cells from healthy individuals and patients with hematological malignancies.
- Comparison of CRP levels between malignant cells and their normal mature counterparts.
Main Results:
- CD35 was predominantly negative in most leukemia cells but present on granulocytes, monocytes, and some lymphocytes.
- CD46 was found in all blood cells except erythrocytes, with significantly higher levels (2-8 times) in most leukemia cells, especially CML and CLL (excluding B-cell lineage).
- CD55, a phosphatidyl inositol-anchored protein, showed decreased expression more frequently in non-Hodgkin lymphoma (NHL) cells compared to other hematological malignancies.
Conclusions:
- Altered expression patterns of CD35, CD46, and CD55 are characteristic of hematological malignancies.
- These changes in complement regulatory proteins may contribute to disease pathogenesis and represent potential therapeutic targets.
Abstract:
The distribution and levels of three membrane proteins, CD35, CD46, and CD55, which serve as complement regulators, were examined in normal peripheral blood and hematologically malignant cells. CD35 was negative in most leukemia cells regardless of the type of leukemia, although granulocytes, monocytes, and some populations of lymphocytes were CD35+. CD46 was present in all blood cells except erythrocytes, and levels were 2-8 times higher in most leukemia cells than in their mature counterparts, particularly in CML and CLL cells, except for those of B cell lineage. CD55, a widely-distributed phosphatidyl inositol-anchored protein, was more frequently lost in NHL cells than in other types of hematological malignancies. In this review, we discuss the roles, mechanisms, and clinical applications of cell-associated complement regulatory proteins in hematological malignancies.