A MURINE MODEL FOR FACTOR VIII ANTIBODY ANTI-IDIOTYPE REAGENTS

Abstract

The regulation of factor VIII antibody (FVIIIAb) production in haemophilic and non-haemophilic patients may be effected by anti-idiotype (Aid) antibodies which specifically react with FVIIIAb. Aid antibodies (reagents) were prepared from rabbits immunised with murine monoclonal FVIIIAb. Immuno fluorescent microscopy and cell culture studies were performed using murine hybridoma cells which secreted the FVIIIAbs.Immuno fluorescence studies examined the ability of the Aid reagents to bind to acetone fixed FVIIIAb secreting hybridoma cells. Positive surface membrane and intra-cytoplasmic staining patterns were seen with the Aid reagent when incubated with the corresponding murine hybridoma cell line. This reaction was blocked subsequent to the addition of the corresponding monoclonal FVIIIAb but was preserved when unrelated monoclonal FVIIIAb was incubated with the hybridoma cells. No fluorescence was observed when Aid reagent was incubated with unrelated FVIIIAb secreting hybridoma cultures.Following the addition of Aid reagent to FVIIIAb secreting hybridoma cultures and incubation for 19 hours, the resultant hybridoma supernatants were examined for FVIIIAb content using an immunoradiometric technique. The Aid reagent failed to inhibit FVIIIAb secretion by hybridoma cells. Thus, although Aid reagents were capable of binding to fixed FVIIIAb secreting cells, they failed to inhibit FVIIIAb secretion from hybridoma cultures. The conjugation of Aid reagent with immunotoxin may however have cytotoxic potential. The murine model provides a method for the study of Aid regulation of FVIIIAb production in haemophilia.