Heterogeneity in human interleukin-3 receptors. A subclass that binds human granulocyte/macrophage colony stimulating factor

125I-Labeled recombinant human interleukin-3 (IL-3) was used to study the characteristics and distribution of receptors for IL-3 on human cells. Receptors were found on primary monocytes, on some strains of KG-1 cells, and on pre-B cell lines. Binding was rapid at 37 degrees C, while requiring sever...

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Bibliographic Details
Published in:The Journal of biological chemistry 1989-04, Vol.264 (10), p.5420-5427
Main Authors: Park, L S, Friend, D, Price, V, Anderson, D, Singer, J, Prickett, K S, Urdal, D L
Format: Article
Language:English
Subjects:
Binding, Competitive
Cell Line
Colony-Stimulating Factors - metabolism
Granulocyte-Macrophage Colony-Stimulating Factor
Growth Substances - metabolism
Humans
interleukin 3
Interleukin-3 - isolation & purification
Interleukin-3 - metabolism
Kinetics
Ligands
lymphoid cells
Receptors, Immunologic - metabolism
Receptors, Interleukin-3
Recombinant Proteins - isolation & purification
Recombinant Proteins - metabolism
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Summary:125I-Labeled recombinant human interleukin-3 (IL-3) was used to study the characteristics and distribution of receptors for IL-3 on human cells. Receptors were found on primary monocytes, on some strains of KG-1 cells, and on pre-B cell lines. Binding was rapid at 37 degrees C, while requiring several hours to reach equilibrium at 4 degrees C. Equilibrium binding studies indicated that IL-3 bound to a single class of high affinity receptor (less than 500 receptors/cell) with a Ka of approximately 1 x 10(10) M-1. Inhibition studies revealed that human granulocyte/macrophage colony stimulating factor partially inhibited the binding of 125I-IL-3 to human monocytes but not JM-1 cells. Additional analysis showed that on KG-1 cells, both IL-3 and GM-CSF partially competed specific binding of heterologous radiolabeled ligand, with approximately equivalent capacities. This competition occurred at both 37 and 4 degrees C. These results suggest heterogeneity in the binding sites for IL-3 and GM-CSF in which a subset of receptors binds only IL-3, a subset only GM-CSF, and another subset can bind both, all with high affinity. Additional heterogeneity was suggested by equilibrium binding of 125I-IL-3 to KG-1 cells which revealed a biphasic Scatchard plot containing a low affinity component not observed on monocytes and JM-1 cells.
ISSN:0021-9258
1083-351X