Flow cytometric detection of receptors for interleukin-6 on bone marrow and
peripheral blood cells of humans and rhesus monkeys
AW Wognum, FC van Gils and G Wagemaker
Erasmus University, Department of Radiobiology, Rotterdam, The Netherlands.
The expression of receptors for interleukin-6 (IL-6) on human and rhesus
monkey peripheral blood and bone marrow (BM) cells was examined by
multiparameter flow cytometry after staining with biologically active,
biotin-labeled human IL-6 and phycoerythrin-conjugated streptavidin.
Consistent with the multiple biologic effects of IL-6 in stimulating immune
functions and hematopoiesis, IL-6 receptors were detectable on a wide
variety of cell types. In peripheral blood, IL-6 receptors were detectable
on monocytes, granulocytes, and on CD4+ T lymphocytes but not on resting,
CD19+ B lymphocytes and CD56+ natural killer (NK) cells. CD8+ T lymphocytes
also expressed IL-6 receptors but at lower levels than CD4+ cells. The IL-6
receptors on granulocytes were only detectable after staining with high
concentrations of biotin- IL-6, suggesting that most IL-6 receptors on
these cells represent low- affinity sites. In contrast, IL-6 receptors on
both CD4+ and CD8+ T lymphocytes were detectable at biotin-IL-6
concentrations as low as 10 pmol/L, indicating that these cells bind IL-6
with high affinity. IL-6 receptor expression patterns on rhesus monkey and
human blood cells were very similar except that receptor levels on
granulocytes were lower in humans than in rhesus monkeys. Similar
differences in expression levels were observed for IL-6 receptors that were
detectable on most granulocyte precursors in the mononuclear fraction of
rhesus monkey and human bone marrow. In addition to these relatively mature
cell types, IL-6 receptors were detectable on a large fraction of human and
rhesus monkey BM blast cells that express the CD34 antigen. The presence of
IL-6 receptors on CD34+ BM blast cells, which are the precursor cells of
most, if not all, BM-derived blood cells, is consistent with the ability of
IL-6, in conjunction with other cytokines, to stimulate immature
hemopoietic cells in vitro and to promote blood cell production when
administered in vivo.
Volume 81,
Issue 8,
pp. 2036-2043,
04/15/1993
Copyright © 1993 by The American Society of Hematology
