DIFFERENTIAL EXPRESSION OF SURFACE-MEMBRANE GROWTH-HORMONE RECEPTOR ON HUMAN PERIPHERAL-BLOOD LYMPHOCYTES DETECTED BY DUAL FLUOROCHROME FLOW-CYTOMETRY

Although several reports indicate proliferative and functional effects of human GB (hGH) on peripheral blood lymphocytes (PBL), no information is available about hGH receptor (GHR) expression in PBL subsets. Here, the surface membrane GHR levels were investigated in different human PBL subpopulations using a fluorescein isothiocyanate (FITC)-conjugated monoclonal antibody specific for the GHR (mAb263) in dual fluorochrome flow cytometric assays. Strong GHR expression was found in B-cells (CD20(+)), whereas CD2(+) lymphocytes, including T-cells as well as natural killer cells, exhibited considerably lower levels of receptor expression. Similarly, using FITC-labeled recombinant hGH, receptor expression on CD20(+) cells was significantly higher than that on CD2(+) cells. Abundant expression of GHR in B-lymphocytes was confirmed by reverse transcriptase-polymerase chain reaction analysis of GHR messenger ribonucleic acid from isolated B-cells. Accordingly, the B-cell merits greater consideration as a GH target cell. The use of FITC-labeled mAb263 and hGH is of potential use for the study of GHR levels in patients exhibiting different types of growth disorders. Because of its high specificity for GHR, FITC-labeled mAb263 is also of considerable value for specifically demonstrating the presence of GHR, because hGH may interact with and act through PRL receptor, as shown previously in human neutrophils.