Immunological studies in the hyper-immunoglobulin D syndrome

Five patients with hyper-immunoglobulin D syndrome (hyper-IgD syndrome) were followed up for 3 to 8 years. In all patients studied, serum IgG₃ was high. IgM decreased during the follow-up in all patients. In four of the patients serum IgA was elevated. In four patients the serum IgD κ/λ ratio was measured and was found to be raised in all. However, the serum total light-chain ratio and IgG, IgA, and IgM κ/λ ratios separately were virtually normal. In two of the patients, clinical symptoms preceded the increase in serum IgD. All patients had a history of severe reactions on immunizations in early childhood. We conclude that in hyper-IgD syndrome, other immunoglobulins may also be affected, in particular, IgA, IgM, and IgG₃. The IgD light-chain ratio is also disturbed. We emphasize that clinical symptoms may herald immunological changes. This may be the result of an underlying factor causing both the clinical symptoms and, later, the increasing serum IgD levels.