Up-regulation of IL-6-receptors by IL-3 on a plasma cell leukaemia cell line which proliferates dependently on both IL-3 and IL-6.

In this report we show that IL-3 up-regulates the expression of IL-6-receptors on a plasma cell leukaemia cell line which proliferates in response to both IL-3 and IL-6. Quantitative binding studies and Scatchard analysis revealed that HSM-2.3 has a single class of high-affinity IL-6 binding sites (200/cell, dissociation constant at the equilibrium 1.43 x 10(-11) M). After stimulation with IL-3, HSM-2.3 has 1200 binding sites. IL-6 receptor mRNA expression was detected in HSM-2.3 only after stimulation with IL-3.