Monitoring of neutrophil priming in whole blood by antibodies isolated from a synthetic phage antibody library

Neutrophil activation is a multistep process. III vitro activation of neutr ophils with semiphyiological activators is optimal only after preactivation or priming with cytokines, chemotaxins, and/or bacterial products. Until n ow, no antibodies have been developed that can dis-tin,guish between restin g and (cytokine) primed neutrophils With a sufficient dynamic range necessa ry for screening clinical samples. We have isolated two human phage antibod ies, designated MoPhab A17 and A27, from a synthetic bacteriophage antibody library. These phage antibodies recognize epitopes that are upregulated on neutrophils present in whole blood treated with low priming concentrations of cytokines, such as GM-CSF and TNF-alpha. This induction was time- and c oncentration-dependent and optimal at concentrations that are sufficient fo r priming functional responses in neutrophils: GM-CSF (10 pM) and TNF-alpha (100 IU/ml). PMNs, isolated from the peripheral blood of chronic obstructi ve pulmonary disease (COPD) patients with a clinical exacerbation, exhibite d a Dar,tial in vivo primed phenotype. These antibodies promise to he an id eal tool to monitor disease activity in whole blood of patients with inflam matory diseases.