The interactions of bone cells with their surrounding extracellular mi
croenvironment may be mediated by integrins, a family of heterodimeric
glycoproteins consisting of a and p subunits that noncovalently inter
act to form cell-substratum adhesion receptors. We previously describe
d the integrins on calvarial bone cells in rats with use of polyclonal
antibodies against some integrin subunits. In the present study, we e
xpanded this initial characterization by employing a more complete pan
el of monoclonal antibodies to identify integrins on human bone cells.
Minced fragments of trabecular bone obtained during total knee arthro
plasty were grown in culture until bone cells became confluent. The ce
lls then were dissociated, plated again, grown to confluence, and assa
yed for alkaline phosphatase activity, response of cyclic adenosine mo
nophosphate to stimulation with parathyroid hormone, and osteocalcin c
ontent. The percentage of the cells that adhered to various substrates
was measured; 60-70% adhered to type-I collagen, fibronectin, vitrone
ctin, and poly-D-lysine; 40-50% adhered to type-IV collagen, laminin?
and gelatin; and only 10% adhered to fibrinogen. Flow cytometric analy
sis with anti-integrin monoclonal antibodies and sodium dodecyl sulfat
e-polyacryamide gel electrophoresis analysis of immunoprecipitates of
the human bone cells revealed high levels of alpha(1) beta(1), alpha(3
) beta(1), alpha(5) beta(1), and alpha(V) beta(5) integrins and much l
ower levels of alpha(2) beta(1), alpha(4) beta(1), alpha(V) beta(1), a
nd alpha(V) beta(3) integrins. This description of the integrin repert
oire of cultured human bone cells represents the first step toward an
understanding of the role played by integrins in the growth, maintenan
ce, and repair of bone.