Detection of somatotropin receptors on human monocytes

The expression of somatotropin receptors on human peripheral blood monocytes was investigated. Binding of [125I]somatotropin to human monocytes was found to be specific and saturable. The binding was rapid and time-dependent, and was abolished by pretreatment of monocytes with trypsin. Scatchard plot analysis revealed that each cell bore more than 8 x 10(3) binding sites with an affinity constant of 1 x 10(8) M-1.