AJP - Renal Physiology, Vol 261, Issue 6 1026-F1032, Copyright © 1991 by American Physiological Society
Multinucleated rat alveolar macrophages express functional receptors for calcitonin
A. Vignery, M. J. Raymond, H. Y. Qian, F. Wang and S. A. Rosenzweig
Department of Orthopedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut 06510.
The fusion of mononuclear phagocytes occurs spontaneously in vivo and leads
to the differentiation of either multinucleated giant cells or osteoclasts
in chronic inflammatory sites or in bone, respectively. Although
osteoclasts are responsible for resorbing bone, the functional role of
giant cells in chronic inflammatory reactions and tumors remains poorly
understood. We recently reported that the plasma membrane of multinucleated
macrophages is, like that of osteoclasts, enriched in
Na-K-adenosinetriphosphatases (ATPases). We also observed that the
localization of their Na-K-ATPases is restricted to the nonadherent domain
of the plasma membrane of cells both in vivo and in vitro, thus imposing a
functional polarity on their organization. By following this observation,
we wished to investigate whether these cells also expressed, like
osteoclasts, functional receptors for calcitonin (CT). To this end,
alveolar macrophages were fused in vitro, and both their structural and
functional association with CT was analyzed and compared with those of
mononucleated peritoneal and alveolar macrophages. Evidence is presented
that multinucleated alveolar macrophages express a high copy number of
functional receptors for CT. Our results also indicate that alveolar
macrophages, much like peritoneal, express functional receptors for
calcitonin gene-related peptide. It is suggested that multinucleated rat
alveolar macrophages offer a novel model system to study CT receptors and
that calcitonin may control local immune reactions where giant cells
differentiate.
