Monoclonal antibody-mediated modulation of parathyroid hormone secretion by dispersed parathyroid cells
J. T. Posillico, R. E. Wilson, S. S. Srikanta, G. S. Eisenbarth, M. Letarte, E. J. Quackenbush, V. Quaranta, S. Kajaji and E. M. Brown
Available data suggest that ionized calcium may interact with a cell
surface "sensor" or "receptor" to produce changes in one or more
intracellular second messengers that ultimately regulate the release of
parathyroid hormone (PTH). Recently, we developed a series of monoclonal
antibodies directed toward specialized differentiation antigens expressed
on endocrine cells. Since many of these monoclonal antibodies displayed
exquisite specificity for cell surface molecules on the parathyroid cell,
we used these reagents as probes to investigate signal
recognition/transduction mechanisms associated with abnormal
calcium-regulated PTH secretion. Depending on their binding site on the
respective target antigen molecules, these monoclonal antibodies either
stimulated or inhibited hormone secretion. Thus, defects in
membrane-associated structures may contribute to deranged calcium-regulated
PTH secretion in abnormal parathyroid cells.
