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Evidence of the existence of a factor that induces C3 receptors on bone marrow cells
Abstract:
The existence of a molecule responsible for the induction of C3R receptors (C3R) on murine bone marrow cells (C3R inducer, C3RI) is demonstrated in lung conditioned media. The inducer of Fc receptors on murine bone marrow cells (FcRI) and the colony-forming factor MGI (macrophage and granulocyte inducer) are also identified from the same source. The three inducing factors are shown by molecular sieving chromatography and by isoelectric focusing in granulated gel to be three different molecules. The molecular weights estimated were of 35,000, 22,000, and 10,500 for C3RI, MGI, and FcRI, respectively, with isoelectric pH values of 3.9, 6.6, and 7.6 for the same molecules. The C3RI is assumed to be of protein nature, because the molecule lost its biologic activity after trypsin or heat treatment. In the two techniques used, the three peaks of activity were completely separated, suggesting that the induction of C3 or Fc receptors and colony formation are mediated by different molecules and thus regulated independently at the cellular level.
Insights
Researchers identified three distinct molecules in lung conditioned media that induce C3 receptors (C3R), Fc receptors (FcRI), and colony formation (MGI) in bone marrow cells, suggesting independent cellular regulation.
Area of Science:
- Immunology
- Cell Biology
- Hematopoiesis
Background:
- Murine bone marrow cells express receptors like C3R and FcRI, and are involved in hematopoiesis.
- Inducing factors for these cellular functions are present in lung conditioned media.
Purpose of the Study:
- To demonstrate the existence and characterize the molecule responsible for inducing C3 receptors (C3RI) on murine bone marrow cells.
- To identify and differentiate C3RI from Fc receptor inducer (FcRI) and macrophage and granulocyte inducer (MGI).
Main Methods:
- Lung conditioned media was used as the source for inducing factors.
- Molecular sieving chromatography and isoelectric focusing in granulated gel were employed for separation and characterization.
- Biologic activity was assessed after trypsin and heat treatment to determine molecular nature.
Main Results:
- Three distinct inducing molecules were identified: C3RI (MW 35,000, pI 3.9), MGI (MW 22,000, pI 6.6), and FcRI (MW 10,500, pI 7.6).
- C3RI activity was lost after trypsin or heat treatment, indicating a protein nature.
- Separation techniques confirmed these are different molecules, suggesting independent regulation pathways.
Conclusions:
- The induction of C3 receptors, Fc receptors, and colony formation are mediated by separate molecular entities.
- These distinct molecules regulate cellular functions independently at the cellular level.
- The identified C3RI is a protein molecule involved in C3 receptor induction.