B CELLS FROM PATIENTS WITH MEMBRANOPROLIFERATIVE GLOMERULONEPHRITIS (MPGN) AND THEIR SIBLINGS ARE PRE-PROGRAMMED TO PRODUCE C3NeF AUTOANTIBODY ASSOCIATED IDIOTYPE. † 2206

Abstract

C3NeF, produced by patients with MPGN, is an autoantibody bearing a specific and singular idiotype. Recently we studied C3NeF production in identical twin girls, one who had MPGN with circulating C3NeF and the other who was entirely normal. Peripheral blood lymphocytes (PBL) were transfected with EBV and mRNA was then obtained followed by cDNA isolation using primers specific for VH. Full length H chain DNA was then inserted into a modified lambda bacteriophage vector and introduced into E.coli to yield an expression library. Detection utilized alkaline phosphatase labelled antibody to a decapeptide inserted into VH and a specific anti-id Ab for C3NeF. Similar studies were done from patients with MPGN and normal individuals using PBL's which were not transfected with EBV. In libraries of 107, both transfected and untransfected cells from normal individuals had 10-12% id-positive VH. Utransfected cells from patients with MPGN had 39% id-positive VH. Transfected cells from patients and both twins were 98% id-positive. These data suggest that patients and family members may be pre-programmed to produce id positive autoreactive IgG.(Supported by funds from the Children's Miracle Network).