Insulin antibodies

The discovery of type 1 diabetes

The etiological heterogeneity of idiopathic diabetes has been recognized for 25 years, and subdivision into type 1 and type 2 diabetes is fundamental to the way we think about the disease. Review of the literature suggests that the concept of type 1 diabetes as an immunemediated disease emerged rapidly over the period from 1974 to 1976 and showed many of the features of a classic paradigm shift. A few key observations triggered recognition and acceptance of the new paradigm, but the necessary context was provided by scientific developments in areas mainly unrelated to diabetes. The disease paradigm established by 1976 is still widely accepted, and its essential features have been modified only in detail by the revolution in molecular biology that has occurred over the intervening period. Notwithstanding, some of the underlying assumptions remain imprecise, unchallenged, or unconfirmed. Appreciation of the historical origin and subsequent evolution of these fundamental concepts could stimulate critical analysis and help prepare the way for a new paradigm.

Beta-cell rest: a strategy for the prevention of autoimmune diabetes

An autoantigen being recognized by specific receptors is the key reaction of an autoimmune disease. Whereas much efforts have been made to develop immunosuppressive regimens which reduce the amount of effector cells, and/or inhibit receptor activation, surprisingly little attention has been paid to reduce the ligand-receptor interaction by interfering with the amount of antigen being presented from the target cells. In this review, we discuss clinical observations in autoimmune endocrine disease which illustrate that target cell alterations can modify the disease activity and comment on recent clinical trials which indicate that beta-cell rest may be beneficial to the course of human autoimmune diabetes mellitus.

Improved haemagglutination reagent for detecting antibodies to insulin in diabetic and non-diabetic young and old patients

A stable reagent of insulin-coated erythrocytes was developed for easy measurement of antibodies to insulin. For this measurement, the principle of graded haemagglutination (GH) was successfully applied. All of 100 healthy, young- to middle-aged controls, had no detectable antibodies. The incidence of antibodies was not higher in diabetic patients injected with highly purified porcine insulin, than in those not injected. A high incidence of antibodies to insulin was found among chronic elderly patients, amounting to 41% of the symptomatically non-diabetic and 77% of the diabetic.

Diabetes and hypoglycemia due to insulin antibodies

A patient with "autoimmune diabetes" with reactive hypoglycemia due to anti-insulin antibodies is described. The pathophysiology of the impaired carbohydrate tolerance and reactive hypoglycemia is illustrated by measurements of C-peptide, and free and antibody-bound insulin. Detailed analysis of her antibodies did not provide any evidence in favor of exogenous insulin immunization. Nevertheless, a possible cause of unsuspected insulin immunization was present in her history which should be considered in other reported cases of "autoimmune diabetes" due to insulin antibodies in which exposure to insulin cannot be documented.

Effects of various drugs on insulin antibodies

1. Insulin antibodies were induced in young guinea-pigs of both sexes weighing 300-400 g and housed in a room maintained at 28 degrees C+/-2 degrees C, by subcutaneous injection of 2 ml of freshly prepared insulin antigen emulsion between the shoulders once every month.2. To estimate the titre of serum antibody the serum was incubated with a known concentration of insulin for 90 min at 37 degrees C and the insulin not bound to antibody was estimated by the rat hemidiaphragm method.3. No significant (P>0.5) development of insulin antibody could be detected in the serum samples collected 1 month after the first and 15 days after the second monthly injections in groups of ten male guinea-pigs and six female guinea-pigs. However, the titre of insulin antibody in the serum of these groups of guinea-pigs 15 days after the third monthly injection of insulin antigen emulsion was significantly (P<0.01) raised. There was no further increase in the titre of insulin antibody in the sera 15 days after the fourth and fifth monthly injections of insulin antigen emulsion. Thus the peak titre was reached 15 days after the third monthly injection of the antigen.4. Two groups of ten male guinea-pigs each received testosterone propionate or diethylstilboestrol daily for 1 week after each monthly injection of insulin antigen emulsion. Two other groups of six female guinea-pigs each received testosterone propionate or diethylstilboestrol in a similar manner. One more group of ten female guinea-pigs received both sex hormones for 1 week after each monthly injection of insulin antigen emulsion. Testosterone facilitated the induction of insulin antibody in the serum of males but did not affect the antibody titre in the female guinea-pigs. Diethylstilboestrol facilitated the induction of insulin antibody in the serum of groups of either sex, the peak titre being attained after the second monthly injection of insulin antigen emulsion. The response of the females which received both sex hormones was similar to that of females which received diethylstilboestrol alone.5. Fifteen days after the third monthly injection of insulin antigen emulsion a group of ten guinea-pigs received hydrocortisone subcutaneously each day for 1 month. The serum antibody titre was estimated at the end of the drug treatment, and was significantly (P<0.01) reduced.6. Fifteen days after the third monthly injection of insulin antigen emulsion three different groups of five-six guinea-pigs each received tolbutamide, chlorpropamide or phenformin orally every day for a month. Antibody titres of the serum were estimated at the end of this period; there was no significant (P>0.05) reduction in groups receiving chlorpropamide or phenformin, but the serum antibody titre of the group receiving tolbutamide was significantly (P<0.01) raised.7. Fifteen days after the third monthly injection of insulin antigen emulsion different groups of five-six guinea-pigs received one of the following: 5-bromouracil, 5-fluorouracil, 6-mercaptopurine, methotrexate, 6-azauridine, busulphan, chlorambucil, cyclophosphamide, actinomycin-D or mytomycin-C intraperitoneally each day for 5 days. The serum antibody titre of all the groups of guinea-pigs was significantly (P<0.01) reduced. On the other hand the serum antibody titre of a control group of six guinea-pigs receiving normal saline intraperitoneally each day for 5 days was not significantly (P>0.5) affected.

Etiologic considerations in peripheral vascular diseases of the lower extremity with special reference to diabetes mellitus

A histopathologic and immunopathologic study of changes in small vessels has been carried out on 168 amputated lower extremities. No difference was found in respect to the frequency of thrombotic or atheromatous lesions among the various clinical disease categories necessitating amputation. An increased frequency of inflammatory lesions of small vessels was found only in cases of osteomyelitis. The frequency of hemodynamic lesions was highest in nondiabetic subjects with arteriosclerosis, and second highest in diabetic subjects with arteriosclerosis, followed by thromboangiitis obliterans. Proliferative endothelial lesions were encountered most frequently in diabetes with arteriosclerosis, in osteogenic sarcoma, and in osteomyelitis. Such proliferative lesions were encountered in 80 per cent of diabetic subjects and in 20 per cent of nondiabetic individuals.

Fluorescent insulin binding by small vessels was found in 70 per cent of diabetic subjects with proliferative vascular lesions and in only 30 per cent of diabetic individuals without this proliferative microangiopathy. Such insulin binding was observed in 54 per cent of diabetic subjects and in only about 15 per cent of nondiabetic patients. The binding of fluorescent rabbit antihuman globulin was observed in 56 per cent of diabetic subjects and in 22 per cent of nondiabetic patients.

These findings are discussed in relation to the thesis that there may be diseases of immune origin primarily involving small peripheral vessels. The peripheral vascular disease of diabetes is particularly stressed here because it is probably the most common form of such disease of immune origin. Such pathologic processes in small vessels may secondarily involve large cognate system arteries, either by creating an increased peripheral resistance to the flow of blood or when lesions involve the vasa vasorum, there may be impairment of local nutrition. Either or both of these phenomena could intensify the development of arteriosclerosis of large trunk arteries.

Although no attempt has been made here to justify or negate the existence of thromboangiitis obliterans as a disease entity, it has been pointed out that at least some cases with this diagnosis may have a similar immune origin.