Monocyte receptors for fibronectin characterized by a monoclonal antibody that interferes with receptor activity
Abstract:
We describe a molecule on the surface of human peripheral blood monocytes that appears to be a plasma membrane receptor for fibronectin. We have identified this protein using a monoclonal antibody, A6F10, which prevents the interaction between monocytes and substrate-bound fibronectin. Thus, at least functionally, the antibody appears to recognize the plasma membrane receptor for fibronectin. The antibody and its Fab fragments bound to the cell surfaces of human monocytes, tissue macrophages, and, to a lesser extent, neutrophils. It did not react with fibroblasts, lymphocytes, platelets, or erythrocytes. It bound human and guinea pig cells but did not react with rat, mouse, or hamster cells. In Western blots, this monoclonal antibody bound specifically to a polypeptide with apparent molecular weight of 110,000 and made of a single chain. The antigen recognized by A6F10 was susceptible to trypsin digestion. These observations suggest that the monoclonal antibody A6F10 is directed to the fibronectin receptor of human monocytes.
Insights
Researchers identified a fibronectin receptor on human monocytes using monoclonal antibody A6F10. This antibody blocks monocyte interaction with fibronectin, indicating it targets the specific cell surface receptor.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Monocytes play crucial roles in immune responses and tissue repair.
- Fibronectin is a key extracellular matrix protein involved in cell adhesion and migration.
- Understanding monocyte-fibronectin interactions is vital for studying inflammatory and immune processes.
Purpose of the Study:
- To identify and characterize the plasma membrane receptor for fibronectin on human peripheral blood monocytes.
- To investigate the functional role of this receptor in monocyte adhesion.
Main Methods:
- Utilized a monoclonal antibody (A6F10) that inhibits monocyte-fibronectin interactions.
- Performed cell surface binding assays on various human and animal cell types.
- Conducted Western blot analysis to determine the molecular weight and characteristics of the antigen.
Main Results:
- Monoclonal antibody A6F10 specifically binds to a 110,000-dalton polypeptide on human monocytes.
- This antigen is also present on tissue macrophages and neutrophils, but not on fibroblasts, lymphocytes, platelets, or erythrocytes.
- The receptor is species-specific, binding to human and guinea pig cells but not rodent cells.
- The identified antigen is susceptible to trypsin digestion.
Conclusions:
- Monoclonal antibody A6F10 recognizes the plasma membrane fibronectin receptor of human monocytes.
- This receptor is a single-chain polypeptide with a molecular weight of 110,000.
- The findings provide a tool for further research into monocyte adhesion and immune cell function.
