Detection of one VH antibody sequence in both healthy donors and urticaria patients

We have previously isolated anti-FcεRIα autoantibodies from phage libraries of healthy donors and urticaria patients. Strikingly, the same antibody, LTMα15, was isolated from both libraries. Sequence analysis revealed a germline configuration of the LTMα15 variable heavy (VH) chain with a slightly mutated variable light (VL) chain supporting its classification as a natural autoantibody. Distribution analysis of anti-FcεRIα autoantibodies by functional or serological tests delivered conflicting data. For this reason we have developed a new real-time PCR to analyse the distribution of LTMα15VH in healthy donors and urticaria patients. Our new bioinformatic program permitted the design of a minor groove binder (MGB) TaqMan probe that specifically detected the LTMα15VH. We were able to demonstrate a broad range of rearranged VH gene copy number without any correlation to the state of health. Monitoring LTMα15VH gene copy number in a single donor over a period of 70 days revealed a time-related fluctuation of circulating B cells carrying LTMα15VH. We propose that our real-time PCR may serve as a model for the quantification of natural antibody sequences at a monoclonal level.