Immunoglobulin concentrations were determined in the sera and nasal washes of 111 patients with
chronic obstructive pulmonary disease who were 45 to 60 years of age and in 111 control subjects matched with the patients for age, sex, occupation, and smoking history who demonstrated normal 1-sec forced expiratory volume. Serum
IgA,
IgM,
IgG,
nad IgE were not significantly different in the 2 groups. Serum
IgD was significantly higher in subjects with
chronic obstructive pulmonary disease. Nasal wash
IgD and
IgM, expressed as percentages of total
protein, were higher in index cases, but nasal wash
IgA and
IgG were comparable in both groups. The finding of relatively high concentrations of
IgA, expressed as fractions of total
protein, in respiratory secretions compared to serum is consistent with earlier findings that
IgA is actively secreted from the respiratory epithelium and is not deficient locally in subjects with
chronic obstructive pulmonary disease. In contrast,
IgM and
IgG expressed as proportions of total
protein were consistently higher in sera than secretions. The
IgE in nasal secretions was detected so seldom in this study that too few matched pairs were available for statistical analysis. The higher concentration of
IgD in the serum and nasal secretions of patients with
chronic obstructive pulmonary disease compared with their matched pairs and the associated higher frequency of low
IgD in control subjects suggests that low
IgD may be protective against the development of
chronic obstructive pulmonary disease. Further studies on the
biologic role of
IgD may provide better understanding of these findings.