Could bovine serum albumin be the initiating antigen ultimately responsible for the development of insulin dependent diabetes mellitus?

Western blotting of either a cloned rat beta-islet tumour cell extract or isolated BB rat islets with rat anti-bovine serum albumin antiserum revealed a cross-reacting protein (Mr = 69,000). A protein of similar molecular size was observed by fluorography in proteins immunoprecipitated from islet cells labelled with (35S)-methionine using anti-bovine serum albumin antiserum. In comparing the primary structure of the beta subunits of the proteins Ia, DQ and DR a region of homology with bovine serum albumin became evident. Analysis of the amino-acid homology in relation to the DR/DQ allotypes found in the human population gave a strong correlation between the combined DR and DQ homology score with bovine serum albumin and the incidence of insulin dependent diabetes mellitus.