Depression of cell-mediated immunity in diabetes.

Parameters of cell-mediated and humoral-mediated immunity were measured in ten infection-free, insulin-dependent, controlled diabetic patients and in ten similar but nondiabetic patients awaiting elective operations. Tests performed included total and differential leukocyte counts, neutrophil reduction of nitroblue tetrazolium, mitogen response of lymphocyte to phytohemagglutinin, ratio of thymus-derived to bone marrow-derived lymphocytes, serum immunoglobulins IgA, IgG, and IgM, macrophage inhibition factor, serum zinc, and reaction to skin test antigens. Diabetics had a significantly (P less than .05) decreased mean response response to phytoheagglutinin stimulation and a lowered ratio of thymus-derived to bone marrow-derived lymphocytes. These findings support the concept of depressed cell-mediated immunity in the controlled, adult diabetic and might explain the propensity of the uncontrolled diabetic to increased frequency and severity of bacterial infection.