Interleukin-3 modulation of mouse bone marrow derived mast cell receptors for somatostatin

Receptors for somatostatin (SOM) were identified on mouse bone marrow derived mast cells (MBMMC) and shown to vary in expression with the state of proliferation and differentiation of the MBMMC. Flow cytometric studies of the binding of fluorescein-labeled SOM and concurrent analyses of the binding of [125I]SOM demonstrated that the population of MBMMC capable of recognizing SOM specifically is that exhibiting a proliferative response to interleukin-3. The MBMMC that bound SOM reached a maximal number at 72 hr following the addition of interleukin-3, and were distributed principally in the G2/M phase of the cell cycle. SOM did not influence directly the proliferative responses of MBMMC to interleukin-3. The level of expression of SOM receptors thus may reflect the state of differentiation of mast cells, as well as determining the functional sensitivity to the inhibitory effects of SOM.