Manganese superoxide dismutase and heat shock protein 70 are not necessary for suppression of apoptosis in human peripheral blood neutrophils.

We have previously shown that granulocyte (G-CSF) and granulocyte/macrophage (GM-CSF) colony-stimulating factors present in human bronchial epithelial cell conditioned medium (HBEC-CM) suppress apoptosis in neutrophils. In this study, we demonstrate that HBEC-CM also induces increased expression of manganese superoxide dismutase (MnSOD) and heat shock protein 70 (HSP70) in neutrophils. However, treatment of neutrophils with recombinant GM-CSF and G-CSF, which suppressed apoptosis to equivalent degrees, did not induce MnSOD or HSP 70. Thus, we conclude that induction of stress proteins is associated with, but not necessary for, suppression of apoptosis.