Structure and biological functions of human IgD. VI. Serum IgD in patients with allergic bronchopulmonary aspergillosis.

Serum IgD levels were quantified in a large population of individuals with a variety of atopic and/or pulmonary disorders. As a group, patients with allergic bronchopulmonary aspergillosis (ABPA) have markedly elevated (5.03 mg%) serum IgD when compared with serum IgD levels from either normal individuals (2.17 mg%) or patients with a variety of pulmonary and/or atopic disorders. Evidence is presented suggesting that the increased serum IgD levels in ABPA patients are not necessarily related to a hyper-IgE or panhyperimmunoglobulinemia common to most of all these patients, but is rather associated with an additional quantitative difference in the immunological responsiveness of some of these individuals. An understanding of why these patients produce supranormal levels of IgD may reveal the basis for inducing an IgD antibody response and subsequently help in elucidating the biological function(s) of IgD.