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Cyclic AMP phosphodiesterases in human lymphocytes
S B Sheth1, K Chaganti, M Bastepe
1Temple University, Sol Sherry Thrombosis Research Center, Philadelphia, Pennsylvania, USA.
British Journal of Haematology
|January 31, 1998
Summary
Lymphocytes utilize cyclic AMP (cAMP) phosphodiesterases (PDEs) for function regulation. PDE3B is identified as the predominant cAMP PDE in lymphocytes, unlike platelets which contain PDE3A.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Intracellular cyclic AMP (cAMP) regulates lymphocyte and platelet function.
- Two high-affinity cAMP phosphodiesterases (PDEs), PDE3 and PDE4, control cAMP levels in hematopoietic cells.
- Understanding lymphocyte PDE activity is crucial for drug development.
Purpose of the Study:
- To determine the relative contribution of PDE3 and PDE4 to total lymphocyte PDE activity.
- To identify which PDE3 gene products (PDE3A or PDE3B) are present in lymphocytes.
- To elucidate the role of cAMP regulation in lymphocyte function.
Main Methods:
- Enzyme activity assays using specific PDE inhibitors (milrinone for PDE3, rolipram for PDE4).
- Reverse transcription polymerase chain reaction (RT-PCR) to detect PDE3A and PDE3B gene expression.
- DNA sequencing to confirm gene identity.
Main Results:
- Lymphocyte PDE activity was predominantly inhibited by the PDE3-specific inhibitor milrinone (70%), with PDE4 inhibition by rolipram at 30%.
- RT-PCR analysis confirmed the presence of PDE3B and the absence of PDE3A in lymphocytes.
- Sequencing revealed >95% identity with PDE3B, indicating it is the major cAMP PDE in lymphocytes.
Conclusions:
- Lymphocytes primarily express PDE3B, a subtype distinct from the PDE3A found in platelets.
- The presence of PDE3B suggests lymphocytes may be subject to hormonal modulation, similar to adipocytes.
- Characterizing cAMP regulation in lymphocytes offers potential avenues for therapeutic drug development.