A fusion protein of IL-8 and a Fab antibody fragments binds to IL-8 receptors and induces neutrophil activation.

Abstract

A fusion protein was generated by genetic engineering which combined a Fab fragment of a monoclonal antibody directed to the human epidermal growth factor receptor with the biologically active N-terminally truncated 2-72 amino acid form of the human chemokine IL-8. The Fab IL-8 fusion protein was expressed in E. coli and antibody binding and IL-8 activity were determined. Our data indicate that the N-terminus of IL-8 remains functional for receptor interaction. The fusion protein showed specific binding to IL-8 receptors, induced IL-8 mediated chemotactic activity, and the release of MPO activity. However, N-terminal fusion of IL-8 to the carboxyl terminus of the Fab fragment resulted in reduced binding to IL-8 receptors and consequently to reduced biologic activity of IL-8. The affinity of the antibody arm for EGF-R was improved when compared to a monovalent Fab. Fusion proteins as described herein may represent improved therapeutics for cancer therapy based on their potential to selectively increase and prolong cytokine concentration in the tumour. Since chemokines such as IL-8 recruit effector cells and stimulate effector cell function in situ, a lymphocyte-independent anti-tumour activity followed by tumour-specific immunity could be proposed.