Iron Inhibits Respiratory Burst of Peritoneal Phagocytes In Vitro

Objective. This study examines the effects of iron ions Fe3+ on the respiratory burst of phagocytes isolated from peritoneal effluents of continuous ambulatory peritoneal dialysis (CAPD) patients, as an in vitro model of iron overload in end-stage renal disease (ESRD). Material and Methods. Respiratory burst of peritoneal phagocytes was measured by chemiluminescence method. Results. At the highest used concentration of iron ions Fe3+ (100 μM), free radicals production by peritoneal phagocytes was reduced by 90% compared to control. Conclusions. Iron overload may increase the risk of infectious complications in ESRD patients

Peritonitis-induced antitumor activity of peritoneal macrophages from uremic patients.

The macrophages belong to the effector cells of both nonspecific and specific immune response. These cells generally express little cytotoxicity unless activated. The present work was intended to determine if peritoneal macrophages collected from patients on Continuous Ambulatory Peritoneal Dialysis (CAPD) during episodes of peritonitis were active against human tumor cell lines without further in vitro stimulation. We also compared macrophage antitumor potential with effectiveness of drugs used in cancer therapy (taxol and suramin). Conditioned medium (CM) of macrophages collected during inflammation-free periods did not exhibit cytostatic and cytotoxic activity against both tumor (A549 and HTB44) and non-transformed (BEAS-2B and CRL2190) cells. Exposure of tumor cells to CM of macrophages harvested during peritonitis resulted in significant suppression of proliferation, impairment of viability and induction of apoptosis, in contrast to non-transformed cells, which remained unaffected. The efficacy of CM of inflammatory macrophages as an antitumor agent appeared to be comparable to cytostatic and cytotoxic potency of taxol and suramin or, in the case of HTB44 cells, even higher. The results obtained suggest that activated human macrophages might represent a useful tool for cancer immunotherapy

Peritonitis-induced antitumor activity of peritoneal macrophages from uremic patients

The macrophages belong to the effector cells of both nonspecific and specific immune response. These cells generally express little cytotoxicity unless activated. The present work was intended to determine if peritoneal macrophages collected from patients on Continuous Ambulatory Peritoneal Dialysis (CAPD) during episodes of peritonitis were active against human tumor cell lines without further in vitro stimulation. We also compared macrophage antitumor potential with effectiveness of drugs used in cancer therapy (taxol and suramin). Conditioned medium (CM) of macrophages collected during inflammation-free periods did not exhibit cytostatic and cytotoxic activity against both tumor (A549 and HTB44) and non-transformed (BEAS-2B and CRL2190) cells. Exposure of tumor cells to CM of macrophages harvested during peritonitis resulted in significant suppression of proliferation, impairment of viability and induction of apoptosis, in contrast to non-transformed cells, which remained unaffected. The efficacy of CM of inflammatory macrophages as an antitumor agent appeared to be comparable to cytostatic and cytotoxic potency of taxol and suramin or, in the case of HTB44 cells, even higher. The results obtained suggest that activated human macrophages might represent a useful tool for cancer immunotherapy

Probing iso-1-cytochrome c structure by site-directed spin labeling and electron paramagnetic resonance techniques

A cysteine-specific methanethiosulfonate spin label was introduced into yeast iso-1-cytochrome c at three different positions. The modified forms of cytochrome c included: the wild-type protein labeled at naturally occurring C102, and two mutated proteins, S47C and L85C, labeled at positions 47 and 85, respectively (both S47C and L85C derived from the protein in which C102 had been replaced by threonine). All three spin-labeled protein derivatives were characterized using electron paramagnetic resonance (EPR) techniques. The continuous wave (CW) EPR spectrum of spin label attached to L85C differed from those recorded for spin label attached to C102 or S47C, indicating that spin label at position 85 was more immobilized and exhibited more complex tumbling than spin label at two other positions. The temperature dependence of the CW EPR spectra and CW EPR power saturation revealed further differences of spin-labeled L85C. The results were discussed in terms of application of the site-directed spin labeling technique in probing the local dynamic structure of iso-1-cytochrome c