Abnormal serum immunoglobulin levels in Down's syndrome patients.

Serum immunoglobulin levels were measured in 20 patients with Down's syndrome and 16 mentally retarded cerebral palsy control patients. Significant elevation of IgG and IgD levels were found in the Down's syndrome as compared with the control patients. Serum IgD level in Down's syndrome individuals significantly decreased with increasing age. Serum IgA level was significantly elevated in older Down's syndrome patients but showed no change in younger Down's syndrome patients. Serum IgM and IgE levels were slightly elevated in Down's syndrome patients, but these differences were not significant. The elevated immunoglobulin levels in Down's syndrome individuals seem to be a response to increased frequency of infection.