Isolation of antibodies which neutralise the activity of early pregnancy factor

Early pregnancy factor (EPF) is a secreted protein with growth regulatory a nd immunomodulatory properties. It functions as an autocrine growth factor for tumour cells and as an autocrine or paracrine growth factor for regener ating normal cells. Anti-EPF antibodies have demonstrable anti-tumour activ ity and, as a result, hybridomas which produce such antibodies are unstable . In this study, the phage display antibody techniques have been investigat ed as a means of producing recombinant anti-EPF antibodies. Mice were immun ised with synthetic peptides which correspond to the N or C terminal region s of EPF, and their splenic tissue was used to make combinatorial antibody libraries. The Fab repertoire was displayed on the surface of phage and pan ned over recombinant EPF. Reactive Fabs were identified by ELISA and their binding was characterised by BIAcore analysis and functional studies. Three libraries with a size of greater than 5x10(7) cfu were constructed and a t otal of 26 unique Fabs with specific reactivity against EPF were identified . Three Fabs were purified and of these one demonstrated strong EPF neutral ising activity, one had intermediate activity and the other was not neutral ising. Phage display has provided the means of circumventing the problems o f anti-EPF hybridoma development and has resulted in the production of anti bodies with potential applications in the diagnosis of pregnancy and the di agnosis and therapy of cancer. (C) 2000 Elsevier Science B.V. All rights re served.