Laron dwarfism: cellular unresponsiveness to GH demonstrated on cultured lymphocytes by a cytochemical method.

The response to growth hormone (GH) of cultured lymphocytes from three patients with Laron dwarfism (LD), one subject with growth hormone deficiency and a normal adult volunteer was examined by employing the cytochemical method of selective silver staining that evidentiates the chromosomal sites of those gene clusters (Nucleolus Organizers, NOs) which are actively involved in rRNA transcription. Lymphocytes from the normal donor responded to GH administration with a significant increase of the mean number of silver positive NOs per cell as well as lymphocytes from the growth hormone deficient patient (P less than 0.001). No response to GH administration was observed in lymphocytes from any of the three subjects with LD. These results suggest that the technique of selective silver staining of NOs can be usefully applied to the study of those growth disorders in which a peripheral unresponsiveness to GH is suspected, as demonstrated by data obtained on lymphocytes from patients with LD. This method seems to offer considerable potentialities for studying the cellular response also to other hormones and environmental stimuli.