IgM and IgD concentrations in the serum and secretions of children with selective IgA deficiency.

Serum IgG and serum and secretory IgM, IgA and IgD levels were determined in 14 children with selective IgA deficiency and in 12 age and sex matched healthy controls. IgD was determined using a highly sensitive ELISA technique. In the healthy controls serum IgG, IgA and IgM were all in the age normal range, and serum IgA was significantly higher than secretory IgA with IgA in nasal secretions being significantly higher than in saliva. In the IgA deficient children serum IgG and IgM and secretory IgM were present in higher concentrations than in the controls but the difference was statistically significant only for serum IgG and salivary IgM. IgD was detectable in the serum and secretions of all patients and all but one control subject. Like IgM, serum IgD levels were significantly higher than secretory IgD levels and IgD was present in greater concentrations in nasal secretions than in saliva both in the patients and the controls, with no difference between the two groups. Thus, the data of this study show that while serum and secretory IgM levels are elevated in children with selective IgA deficiency, serum and secretory IgD are present in normal concentrations, supporting the hypothesis of a compensatory increase in IgM but not in IgD in such patients.