The mechanism of Ca++ dependence of rat peritoneal macrophage IgM-Fc receptor activity was examined. We found that both cell surface bound and intracellular free Ca++ play an important role in the interactions between multivalent IgM complexes and macrophages. On the other hand, Ca++ is not required for binding of native IgM molecules by macrophages. These data support the concept that the IgM-Fc receptor cluster formation itself rather than the receptor - IgM Fc interaction is Ca++ dependent.
ASJC Scopus subject areas
- Molecular Biology