Mf. Brizzi et al., REGULATION OF POLYMORPHONUCLEAR CELL ACTIVATION BY THROMBOPOIETIN, The Journal of clinical investigation, 99(7), 1997, pp. 1576-1584
Thrombopoietin (TPO) regulates early and late stages of platelet forma
tion as well as platelet activation, TPO exerts its effects by binding
to the receptor, encoded by the protooncogene c-mpi, that is expresse
d in a large number of cells of hematopoietic origin, In this study, w
e evaluated the expression of c-Mp1 and the effects of TPO on human po
lymorphonuclear cells (PMN), We demonstrate that PMN express the TPO r
eceptor c-Mp1 and that TPO induces STAT1 tyrosine phosphorylation and
the formation of a serum inducible element complex containing STAT1, T
he analysis of biological effects of TrO an PMN demonstrated that TPO,
at concentrations of 1-10 ng/ml, primes the response of PMN to n-form
yl-met-leu-phe (FMLP) by inducing an early oxidative burst, TPO-induce
d priming on FMLP-stimulated PMN was also detected on the tyrosine pho
sphorylation of a protein with a molecular mass of similar to 25 kD. M
oreover, we demonstrated that TPO by itself was able to stimulate, at
doses ranging from 0.05 to 10 ng/ml, early release and delayed synthes
is of interleukin 8 (IL-8), Thus, our data indicate that, in addition
to sustaining megakaryacytopoiesis, TPO may have an important role in
regulating PMN activation.