Neutrophil dysfunction in end-stage renal failure: reduced response to priming by C5a

We studied the effect of C5a pretreatment on phosphatidyl-inositol-4,5-bisphosphate (PIP2) hydrolysis and on the increase in peak and resting cytosolic calcium levels induced by C5a (0.1 and 10 nM) and/or N-formyl hexapeptide (FLPEP; 10 nM) in neutrophils isolated from patients with end-stage renal failure (ESRF) and those from healthy controls. We also investigated superoxide anion production under the same conditions using the fluorescent para-hydroxyphenylacetic acid assay. The hydrolysis of PIP2 induced by C5a or FLPEP alone was similar in neutrophils from patients with ESRF and in control cells. Likewise, pretreatment of patients' neutrophils with C5a prior to FLPEP did not affect hydrolysis or the increase in cytosolic calcium concentration as shown previously for control neutrophils. Resting calcium levels in both ESRF and control neutrophils, however, were significantly increased after priming with low C5a concentrations. After priming with low C5a, prior to FLPEP, there was also a significant increase in superoxide production. This increase was significantly lower in cells from uremic patients than in those from healthy controls. Our data suggest that priming-induced superoxide production in neutrophils is reduced in patients with ESRF.