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Evidence for specific annexin I-binding proteins on human monocytes
N J Goulding1, L Pan, K Wardwell
1Department of Biochemical Pharmacology, Medical College of St. Bartholomew's Hospital, London, U.K.
The Biochemical Journal
|June 1, 1996
Summary
Annexin I binds specifically to monocytes, not lymphocytes. This interaction involves identified surface proteins and may explain how annexin I reduces inflammation.
Area of Science:
- Immunology
- Cell Biology
Background:
- Annexins are a family of calcium-dependent phospholipid-binding proteins.
- Annexin I plays a role in regulating inflammatory processes.
Purpose of the Study:
- To investigate the specific binding of recombinant human annexin I to peripheral blood monocytes.
- To identify annexin I-binding proteins on the monocyte surface.
Main Methods:
- Flow cytometry was used to analyze annexin I binding to monocytes and lymphocytes.
- Monoclonal antibodies were employed to block annexin I binding and assess its functional relevance.
- Surface iodination, immunoprecipitation, and SDS/PAGE were utilized to identify binding proteins.
Main Results:
- Annexin I exhibited trypsin-sensitive, saturable binding to human peripheral blood monocytes, but not lymphocytes.
- A blocking monoclonal antibody inhibited annexin I's anti-phospholipase activity and its binding to monocytes.
- Two annexin I-binding proteins with molecular masses of 15 kDa and 18 kDa were identified on the monocyte surface.
Conclusions:
- Peripheral blood monocytes possess specific binding sites for annexin I.
- The identified annexin I-binding proteins are crucial for annexin I-monocyte interactions.
- Understanding these interactions can elucidate annexin I's role in down-regulating pro-inflammatory monocyte functions.