Anti idiotypic recognition of auto and allo antibodies to factor VIII by immunoglobulin preparations from single blood donors and large plasma pool.

Therapeutic immunoglobulins from commercial origin were administered to patients with allo and auto antibodies to factor VIII. The protocol used was similar to the prescription suggested for ITP, 0.4 g/kg body weight for five consecutive days. In patients with auto antibodies two kinds of effects were observed: A direct interaction between IVIg and the factor VIII inhibitor and long term interaction on antibody synthesis. The direct interaction observed in vivo was demonstrated to be mediated through Fab'2 fragments of both idiotypic interaction. This was also demonstrated using binding experiments and affinity chromatography experiments: Fab'2 fragments of IVIg were coupled to sepharose and Fab'2 fragments of patients IgG with allo and auto antibodies to Factor VIII were circulated through the column. The recovery of anti Factor VIII antibodies after elution was possible in 2 cases of allo antibodies out of 3 tested and 3 cases of auto antibodies out of 4. The question of anti idiotypes against factor VIII inhibitors in single individuals was investigated. IgG and Fab'2 fragments from single blood donors were isolated and tested for their inhibitory capacity against Fab'2 fragments of three different auto antibodies. The results did not show statistical differences between males and females however in the group of male blood donors, aging was a positive parameter for the presence of anti idiotypic antibodies against factor VIII inhibitors. Anti idiotypic antibodies against factor VIII inhibitors were present in 17.2% of the blood donor tested.