Quantitative Determination of Serum Immunoglobulin D in Gammopathy

Abstract

Serum immunoglobulin D (IgD) level was determined in 10 normal subjects, 5 cases of IgD-myeloma and 23 cases of various autoimmune diseases by the antibody-agar plate method using the antiserum against the heavy chain of IgD, which had been prepared in a rabbit immunized with an IgD-myeloma protein. The serum IgD level was below 0.05 mg/ml in normal subjects and above 10mg/ml in IgD-myeloma cases. In one case, IgD levels were serially followed; the level dropped to 1.0mg/ml by administration of cyclophosphamide. More than a half of cases of various autoimmune diseases showed the serum IgD levels of above 0.05 mg/ml. The highest level in this autoimmune disease group was 0.14 mg/ml in a case of aortitis. All of the 4 cases of aortitis studied showed IgD levels of above 0.05 mg/ml. Whether serum IgD elevation in autoimmune diseases is an expression of general elevation of immunoglobulins or represents the elevation of antibodies specific for these diseases awaits further studies. © 1968, Tohoku University Medical Press. All rights reserved.