Studies on hematopoietic growth factor receptors using human recombinant IL-3, GM-CSF, G-CSF, M-CSF, IL-1 and IL-4.

An increasing number of cytokines including GM-CSF, G-SCF, M-CSF, IL-3, IL-1 and IL-4, have been implicated in the control of the growth and differentiation of hematopoietic cells. The characterization of the cell surface receptors for these proteins is described. The binding of rh IL-3 to human monocytes is described in some detail, and the binding parameters measured for this cytokine are compared with those determined for the other cytokines. The range of cells to which rh IL-3, rh GM-CSF and rh G-CSF bind is more restricted than that observed for the cytokines IL-1 and IL-4, which bind to a diverse spectrum of cell types. Practical applications of receptor studies include the determination of receptor affinity as a measure of recombinant cytokine potency and the use of the receptor ligand interaction to establish sensitive radioreceptor assays for the detection of cytokines in solution. Finally, methods used for the molecular characterization of cytokine receptors are described and summarized for the CSF receptors, IL-4 and IL-1.