Related Experiment Videos
The heterogeneity of Fc receptors on human peripheral mononuclear blood cells
Abstract:
Fc-receptor positive peripheral blood mononuclear cells (PMBC) behaved differently after a temperature shift from 4 to 37 degrees. Two types could be distinguished. Type I FcRI+PMBC were transformed to FcR-while type II FcRII+PMBC retained their FcR as measured by EA rosettes. The supernatants of the PMBC or the shed receptor purified on a Sepharose 4B-aggregated human IgG column blocked the EAR formation of FcRI+PMBC but had no effect on EAR information of FcRII+PMBC. An investigation was made into the reason why rosette formation by Fcrii+ cells could not be inhibited by FcRI. As an explanation, the role of differences in affinity or subclass specificity was excluded while the binding site(s) on the IgG molecule for FcRI and II proved to be different. The FcRII+PMBC had a greater cellular avidity for sensitized erythrocytes than FcRI+PMBC. The different states of FcR-s in the cell membrane are discussed as a possible source of heterogeneity.
Insights
Peripheral blood mononuclear cells (PMBC) show distinct behaviors after temperature changes. Type I FcRI+ PMBC lose Fc receptors, while Type II FcRII+ PMBC retain them, indicating cell membrane heterogeneity.
Area of Science:
- Immunology
- Cell Biology
Background:
- Peripheral blood mononuclear cells (PMBC) express Fc receptors (FcR) that mediate immune responses.
- Fc receptor expression and function can be influenced by environmental factors like temperature.
- Heterogeneity in FcR expression on PMBC suggests distinct functional roles.
Purpose of the Study:
- To investigate the differential behavior of Fc receptor-positive PMBC after a temperature shift.
- To characterize the distinct types of FcR+ PMBC and their response to temperature changes.
- To elucidate the mechanisms underlying the observed differences in Fc receptor function.
Main Methods:
- Temperature shift experiments (4°C to 37°C) on FcR+ PMBC.
- Measurement of Fc receptor expression using EA rosettes.
- Analysis of supernatant and purified shed receptors for inhibitory effects on rosette formation.
- Investigation of Fc receptor affinity, subclass specificity, and IgG binding sites.
Main Results:
- Two distinct types of FcR+ PMBC were identified: Type I FcRI+ PMBC transformed to FcR-, and Type II FcRII+ PMBC retained FcR.
- Supernatants and shed receptors from PMBC inhibited FcRI+ PMBC rosette formation but not FcRII+ PMBC.
- Differences in IgG binding sites, not affinity or subclass specificity, explain FcRI's inability to inhibit FcRII+ cell rosette formation.
- FcRII+ PMBC exhibited greater cellular avidity for sensitized erythrocytes than FcRI+ PMBC.
Conclusions:
- Temperature-induced changes reveal heterogeneity in Fc receptor expression and function on PMBC.
- Distinct Fc receptor states on the cell membrane contribute to functional differences.
- FcRII+ PMBC possess higher avidity, suggesting a distinct role in immune surveillance.