Susceptibility to Leukemia: Immunologic Factors in Down's Syndrome

Summary

In an effort to define Factors associated with an increased susceptibility to leukemia in patients with Down's syndrome, we conducted a controlled study of immunologic and hematologic differences between the Down's syndrome population and other mentally retarded controls. Of 63 patients tested, those with Down's syndrome had a lower index of skin reactivity (principally related to mumps and tuberculin tests), a higher basophil count, and an exaggerated leukocytosis 90 minutes aFter epinephrine injection than the controls. Although some of these differences were small, all were statistically significant (P < 0.05). A tuberculin test survey of 1,262 residents of an institution for the mentally retarded revealed a lower Frequency of skin reactions among the patients with Down's syndrome (17.2%) than among the other mentally retarded subjects (23.0%) (P = 0.054). Previous studies revealed a defect in small lymphocyte function and an excessive immunoglobulin G response in patients with Down's syndrome. A hypothesis is proposed that susceptibility to leukemia is associated with impaired cellular immunity, and that other (possibly compensatory) responses may be exaggerated.