Cross-linking reagents were used to further characterize the murine B cell receptor for the Fc portion of
IgE (Fc epsilon R) and compare this receptor to the well-characterized high-affinity Fc epsilon R on rat basophilic
leukemia (RBL) cells. The
disulfide cleavable and noncleavable
reagents 3,3'-dithiobis(sulfosuccinimidyl)
propionate (
DTSSP) and
bis(sulfosuccinimidyl) suberate (BS3) were used. With these
reagents, efficient cross-linking of the alpha component of the high-affinity RBL Fc epsilon R to the membrane-buried beta and gamma components occurred only if the membrane was solubilized before the cross-linking reaction. In studies with purified murine B cells,
IgE could be cross-linked to the Fc epsilon R on intact cells with either
DTSSP or BS3. Under the same conditions, up to 10% of the B cell
surface immunoglobulin (sIg) (both
IgM and
IgD) was also found to cross-link to a portion of the
IgE/Fc epsilon R complex, suggesting that on the intact murine B cell the Fc epsilon R is frequently in close association with sIg. The B cell Fc epsilon R was also examined for the presence of receptor-associated
proteins. Under conditions where the high-affinity RBL Fc epsilon R was substantially cross-linked to the alpha, beta, gamma complex, no evidence was seen for similar cross-linking of the B cell Fc epsilon R. Cross-linking experiments on affinity-purified Fc epsilon R preparations also gave no evidence for receptor-associated
proteins with the B cell Fc epsilon R, although evidence for receptor-receptor association was seen. Thus, these data further support the concept that there may be little relationship between the high-affinity mast cell/basophil Fc epsilon R and the low-affinity lymphocyte Fc epsilon R.