“…From our experience over the last ten years with indirect IF in several clinical conditions such as chronic thyroiditis, myasthenia gravis and pemphigus [11,12,13], we have learned to avoid using sera in low dilutions and especially undiluted serum. A few pilot experi ments performed at the beginning of this study with sera diluted 1:3 gave a high incidence of nonspecific staining, leading us once again to the use of higher dilutions, starting with 1:10.…”