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 informati on is available about hGH receptor (GHR) expression in PBL subsets. He re, the surface membrane GHR levels were investigated in different hum an PBL subpopulations using a fluorescein isothiocyanate (FITC)-conjug ated monoclonal antibody specific for the GHR (mAb263) in dual fluoroc hrome flow cytometric assays. Strong GHR expression was found in B-cel ls (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 e xpression 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 messen ger ribonucleic acid from isolated B-cells. Accordingly, the B-cell me rits greater consideration as a GH target cell. The use of FITC-labele d mAb263 and hGH is of potential use for the study of GHR levels in pa tients 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.