Expression of a Human Fetal Anti-DNA Antibody Idiotype BEG-2β in the Families of Patients with Rheumatoid Arthritis

BEG-2 is a monoclonal antibody produced by the human-human hybridoma technique from a 12 weeks old human fetus. A polyclonal antiserum was raised in an (NZW x Half-lop hybrid) rabbit against BEG-2 and the anti-BEG-2 anti-idiotype was purified and characterised. Using this rabbit reagent the expression of the BEG-2 beta idiotype was analysed in 12 patients with active rheumatoid arthritis and their close family members (n = 54). Twenty five sera from healthy controls were analysed to establish a normal range. Ten of 12 patients (83%) with rheumatoid arthritis expressed the BEG-2 idiotype as well as 11 of 54 healthy unaffected relatives (20%).