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The rat basophilic leukemia (RBL) cell lines were cloned and the various sublines compared for their chromosome number, IgE-mediated histamine release and for IgE surface receptors. It was found that cell lines started from tumors at different times vary in both their chromosome number and their ability to release histamine by an IgE-mediated reaction.(More)
We have evaluated the effect of ligand binding on expression of the receptor for IgE on rat basophilic leukemia (RBL) cells. RBL cells were grown in the presence or absence of 131I-labeled IgE and sometimes were also surface labeled with 125I. We found that cells grown in the presence of IgE continued to accumulate receptors at the surface and thus the(More)
We have previously shown that, unlike monomeric IgE, chemically derived dimers, trimers, and heavier oligomers of IgE were internalized efficiently. This finding suggested that endocytosis, like mediator release, is triggered by cross-linking of the cell surface receptors for IgE. In the present study, we analyzed the temporal and functional relationships(More)
Rat basophilic leukemia cells (RBL-2H3) have receptors for immunoglobulin E (IgE) and immunoglobulin G (IgG). These receptors for IgE mediate the endocytosis of chemically or immunochemically cross-linked IgE but not monomeric IgE. However, unoccupied receptors were endocytosed with cross-linked IgE. To further assess the degree and specificity of the(More)
The sequences of the 35 and 36 amino-terminal amino acids of two purified amyloid fibril proteins have been determined. Results indicate that these two proteins are derived from homogeneous immunoglobulin light chains of variable region subgroup V(kappaI). The relation between amyloidosis and immunoglobulins is thus more firmly established.
Catechol-O-methyltransferase (COMT) was visualized in homogenates and subcellular fractions of rat tissues, including liver and brain, by gel electrophoresis, electrophoretic transfer of proteins to nitrocellulose (Western blotting), and immune fixation with antiserum to highly purified soluble rat liver COMT. Sodium dodecyl sulfate-polyacrylamide gel(More)
We have assessed the internalization of variously sized oligomers of IgE bound to rat basophilic leukemia (RBL) cells by measuring their accessibility to the extracellular environment, and by direct visualization of the radiolabeled ligands. We also followed the fate of the internalized ligands and their receptors, as well as the fate of the free receptor(More)
Cell surface receptors for IgE were isolated from detergent lysates of iodinated, IgE-saturated, rat basophilic leukemia cells by precipitation with anti-IgE antibodies followed by chromatography at acid pH. The isolated material showed a single 125I-band (m.w. approximately 58,000) on gel electrophoresis in sodium dodecyl sulfate and was used to immunize a(More)
The rat basophilic leukemia cell line (RBL-1) showed an inverse relationship between growth rate and expression of receptor activity for IgE. After prolonged exponential growth, the number of receptors per cell stabilized at 4-6 times 10-5. Cells in stationary cultures, which are arrested in the G1 phase of the cell cycle, continued to accumulate up to(More)
In order to develop a reagent capable of killing cells with high-affinity IgE Fc receptors, such as mast cells and basophils, ricin A-chain (the toxic portion of ricin) was conjugated to rat IgE myeloma protein, IR 162, via derivatization of the IgE by n-succinimidyl-3-(2-pyridyldithio)propionate (SPDP) thus creating an IgE-immunotoxin. Monensin(More)