Peripheral T-lymphocytes in juvenile-onset diabetics (JOD) and in maternity-onset diabetics (MOD)

Neutrophil and lymphocyte function in patients with diabetes mellitus

Neutrophil granulocyte chemotaxis and intraneutrophilic and plasma levels of lysozyme as well as the number of T and B lymphocytes and lymphocyte transformation in vitro on stimulation with mitogens and microbial antigens were studied in four groups of patients with diabetes mellitus (DM). Twelve patients with insulin-dependent diabetes mellitus (IDDM) and ketoacidosis and 4 patients with non-insulin-dependent diabetes mellitus were studied at the time of diagnosis and before and after start of treatment. Ten patients with IDDM of less than 10 years' duration which had been difficult to regulate well and 10 patients with IDDM well regulated for more than 20 years were studied at their regular outpatient visits. Apart from a slight increase in plasma lysozyme in group 1 from the first to the second examination, we found no differences between diabetics and healthy control persons. It is concluded that if patients with DM are more susceptible to infections, it is probably caused by elements of neutrophil or lymphocyte function not examined in this study or by factors unrelated to immunity.

Humoral immune response in hereditary and overt diabetes mellitus

The inbred diabetic mutant mouse, C57BL/KsJ db +/db + (db +/db +), spontaneously develops diabetes mellitus when allowed food ad libitum. However, restriction of food intake prevents the expression of this genetic predisposition for diabetes. This experimental design has been used previously to demonstrate a deficient neutralizing antibody response to coxsackievirus B4 (CB4) in mutants with the genetic predisposition only. These observations demonstrate that in the genetically predisposed diabetic mutant, deficient humoral immunity extends further to a general impairment in both total IgM and IgG production after CB4 infection. Furthermore, these mice are unable to produce a virus-specific IgG response but do show a high level of nonspecific antibody suggesting a polyclonal activation following CB4 challenge. In addition, we observed an increase in the number of spleen IgM antibody-forming cells to sheep erythrocytes (SRBC) in the overtly diabetic animal following CB4 infection with little change apparent in the genetically predisposed animal after infection. These results were identical to the changes seen in total spleen cell numbers. Our animal model provides an opportunity to distinguish between the genetic predisposition to diabetes and the overt disease and suggests that some of the immune impairment found prior to diabetes onset may be partially diminished afterwards.

Recovery of the immune system in diabetic mice after transplantation of isolated islets of Langerhans

Adult CBA/HZgb mice islets harvested by collagenase digestion were injected intraperitoneally in 52 singeneic diabetic recipients (CBA/Hgb leads to CBA/HZgb, 450-600 islets per mouse). Normal serum glucose levels, 24-h urine volume, insulin levels and body weight were completely restored to normal in all recipients during the next 2-5 months. Immunological function was assessed in control, diabetic and diabetic-transplanted mice by following their responses to sheep erythrocytes (expressed as the number plaque-forming cells in the spleen). In transplanted mice, the plaque-forming cell responses were as follows: 1 month after transplantation--43% of the plaque-forming cell counts in control (normal, non-diabetic) mice; 2 months after transplantation--56% of the control value; and 94% of the control value after 5 months. Ten months after the transplantation, the plaque-forming cell counts were slightly above the control value (148%). It appears, therefore that transplantated islet tissue positively affects the immunological as well as the diabetic state of the recipients.

Hematologic alterations in diabetes mellitus

Several hematologic abnormalities have been defined in patients with diabetes mellitus, despite the lack of classic hematologic pathologic findings in this condition. Studies of the erythrocyte and the formation of hemoglobin A1c have provided a means of documenting glycemia and a model reaction for diabetic sequelae through postsynthetic protein modification. Oxygen affinity has been noted to be abnormal in the diabetic erythrocyte, concomitant with a decreased concentration of inorganic phosphorus, glycosylation of the 2,3-diphosphoglycerate binding site or preexisting vascular disease. Red cell membrane viscosity has also been documented to be increased in the hyperglycemic subject. Abnormalities in the polymorphonuclear leukocyte have been described, involving the properties of adherence, random migration, chemotaxis, phagocytosis and killing. Certain metabolic abnormalities are also present in this cell type. The lymphocyte has been shown to have abnormal metabolic properties, mitogen responses and cell surface properties in diabetes both in animals and human subjects. Certain subpopulations of lymphocytes appear to be especially vulnerable to changes concomitant with diabetes mellitus. In vitro abnormalities of platelet behavior have been widely studied, although the in vivo significance of these findings remains controversial. Studies of the fluid phase of coagulation have suggested the existence of a hypercoagulable state in hyperglycemic subjects. The clinical significance of most of these findings remains to be defined. Nevertheless, the observation that many of the abnormalities described are reversible when hyperglycemia is corrected has given impetus to the development of improved systems of glucose "control" for diabetic patients.

Lymphocyte subpopulations in insulin-dependent diabetics with and without serum islet-cell autoantibodies

The lymphocyte subpopulations of 26 insulin-dependent diabetics were studied. Thirteen of them had persistent pancreatic islet-cell serum antibodies (ICA) (mean (+/- SD) duration of diabetes 11 +/- 8 years). The others were ICA-negative (mean duration of diabetes 10 +/- 8 years). The mean fasting blood glucose in the week before the lymphocyte count was 1..37 +/- 0.45 g/l (two specimens for every patient). As controls 19 healthy volunteers, sex and age matched, were investigated. The T-lymphocyte count was no different in diabetics compared to controls. B-cells were significantly raised (p less than 0.01) in the ICA-positive group, when tested with anti-human gammaglobulin sera (IgG + IgA + IgM), anti-human IgM, while no difference was observed between ICA-negative patients and normal subjects. IgA-bearing lymphocytes were equally raised in both diabetic groups (p less than 0.05). These data show an altered immunological balance in type IB (autoimmune) diabetes, characterized by an increased number of B-lymphocytes.

Induction of chronic diabetes by streptozotocin in the miniature pig

The rapid i.v. injection of 60 mg streptozotocin/kg body weight 8 days after an initial dose of 30 mg/kg was the best method to produce a distinct insulin-deficient diabetes in minipigs. Even in the absence of any therapy the further course of this diabetes remained stable without tending to exhibit ketoacidosis. Besides hyperglycaemia and the loss of insulin response to glucose there was significant increase of triglycerides and a decrease of plasma albumin. In the oldest animals this diabetes has so far been observed for more than 3 years. Because of some special advantages this experimental diabetes could provide a useful model for studying diabetic angiopathies.

Circulating lymphocyte subpopulations in juvenile insulin-dependent diabetes. Correction of abnormalities by adequate blood glucose control

Circulating lymphocytes from 39 juvenile insulin dependent diabetics of recent onset were studied by six membrane marker techniques and mitogen stimulation. Well controlled (n = 14) were grouped separately from poorly controlled (n = 25) patients. The total lymphocyte counts were not different from 50 control subjects. The percentage of T-cells detected by erythrocyte rosettes and B-cells detected by erythrocytes--antibody--complement rosettes was significantly decreased only in poorly-controlled diabetics (64.1 +/- 1.3 and 9.7 +/- 1.8, vs 71.0 +/- 1.0 and 15.3 +/- 0.6 in controls). Cells bearing receptors for the Fc fragment of IgG immunoglobulins were decreased in both groups. Mitogen stimulation was not different from controls but was significantly lower in poorly controlled than in well controlled diabetics. Optimal blood glucose control for 5 +/- 2 days using an external artificial pancreas led to a rapid normalisation of membrane marker values and mitogen responsiveness of lymphocytes from previously poorly controlled diabetics. Separate in vitro experiments showed that glucose had an inhibitory effect on mitogen stimulation at concentrations greater than or equal to 8.3 mmol/l and on T- and B-lymphocyte numbers at concentrations greater than or equal to 55.6 mmol/l. DL 3-hydroxybutyrate tested at 17.1 and 34.2 mmol/l only depressed mitogen responsiveness. Such results suggest a rapidly reversible T-cell defect closely linked to the existing metabolic disturbances.