Hyperimmunoglobulinaemia D and periodic fever: a new syndrome.

Six patients of Dutch ancestry with a long history of recurrent attacks of fever of unknown cause were found to have a high serum IgD level and a large number of plasma cells with cytoplasmic IgD in the bone marrow. Because the clinical picture in some ways resembled that of familial Mediterranean fever (FMF), sera of patients with FMF were also investigated; only one of eight such patients had a raised serum IgD.