Insulin resistance in juvenile diabetes mellitus. Immunologic studies

Drug-induced immune hemolytic anemia

BACKGROUND

Drug-induced immune hemolytic anemia is frequently associated with serious complications.

OBJECTIVE

To identify which drugs are implicated in drug-induced immune hemolytic anemia, how they stimulate the production of antibodies and how they could be identified.

METHODS

Individual studies were selected from Pubmed and Scholar databases without any time restrictions placed on the studies. All English language reports including those from the cross-references (approximately 560) were carefully studied. The results of the most relevant clinical and serological studies in this field are summarized and discussed in this review.

RESULTS

Drugs may lead to the production of two types of antibodies. One type reacts with red blood cells (RBCs) only in the presence of the drug and/or its metabolites, and predominantly causes complement-mediated intravascular hemolysis. The second type reacts with RBCs, also in the absence of the drug, belongs to the IgG class, does not activate complement and causes Fc-mediated extravascular hemolysis. Some drugs may stimulate the production of both types of antibodies. Meanwhile, > 130 drugs have been reported to be the cause of immune hemolytic anemia (IHA) but the data are frequently incomplete or implausible.

CONCLUSION

The number of drugs involved in inducing IHA is increasing. However, the vast majority of these drugs seem to cause IHA only in isolated cases. Based on the number of reports in the literature, new drugs that most frequently cause IHA are the new generation of cephalosporins, diclofenac, oxaliplatin and fludarabin.

Drug-induced red cell dyscrasias

Major advances have been made in recent years in our understanding of the pathogenetic mechanisms of drug-induced blood dyscrasias, particularly those involving the red cell. Among the latter, hemolytic anemia is the most common. Drug-induced red cell destruction may occur on an immune basis or through disruption by the drug of red cell metabolism. The immunological basis of drug-induced hemolysis is reviewed with emphasis on the clinical and laboratory manifestations, differential diagnosis and the major mechanisms involved. Drug-induced oxidative hemolysis both in normal individuals and in those with certain enzymopathies, notably glucose-6-phosphate dehydrogenase deficiency, is summarized. Drugs may also produce red cell dyscrasias by acting on the immature erythroid compartment. Some of these inhibit erythroid growth by as yet poorly understood mechanisms. Others exert more specific metabolic effects in erythroid precursors. These include drugs which interfere with DNA synthesis causing megaloblastic erythropoiesis and those which disrupt mitochondrial function and the synthesis of heme manifested by sideroblastic erythropoiesis. A brief consideration of heme biosynthesis and the action of drugs which are associated with sideroblastic anemia, including the antituberculous agents, lead, alcohol and chloramphenicol is presented. Finally, where pertinent, an updated listing of drugs involved in red cell dyscrasias is included.

Monoclonal gammopathy with an insulin binding IgG(K) M-component, associated with severe hypoglycaemia

A case is described in which a monoclonal gammopathy was associated with postprandial hypoglycaemia, resulting from insulin binding by the M-component. The monoclonal immunoglobulin possessed a low affinity for insulin, but its binding capacity was very high. Cytotoxic chemotherapy and diazoxide treatment failed to prevent severe hypoglycaemic attacks.

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.

B and T cell surface markers on peripheral lymphocytes from diabetic patients

A study of T and B cell surface markers was carried out on peripheral blood lymphocytes from diabetic patients, employing immunofluorescent staining for membrane Ig, and the E rosette test. According to the immunofluorescent studies the % of sIg bearing lymphocytes decreases with age; this trend is more evident in healthy individuals. Lymphocytes from diabetic patients posses a higher amount of membrane IgG than age-matched controls. It was only in the younger diabetic patients that a definite decrease was observed in the % of IgM bearing lymphocytes. The evaluation of E rosette-forming lymphocytes revealed a similar age-associated reduction both in diabetics and in controls. Some common features of the pattern of T and B cell markers on lymphocytes from younger diabetic patients and older controls suggest that the former undergo, at least from the immunological standpoint, a more precocious ageing process. It is possible that some metabolic disorders in lymphocyte activity may play a role in this, resulting in a deficiency in the control of immunological mechanisms.

Drug-induced immune hemolytic anemia

Drug administration causes from 16 to 18 per cent of cases of acquired immune hemolytic anemia. The pathogenesis of erythrocyte sensitization by drug-related antibody with or without fixation of complement is variable, and there is a relationship between the responsible drug, the mechanism of red cell sensitization, clinical manifestations and laboratory methods of diagnosis. Drugs such as phenacetin and quinidine form a complex with the antidrug antibody, and the immune complex attaches to red cells usually fixing complement and causing acute intravascular hemolysis. Other drugs (e.g., penicillins), when given in large doses, coat normal red cells in vivo and in some patients a high titer IgG anti-drug antibody develops which reacts with the coated cells. Hemolytic anemia may develop with red cell destruction being primarily extravascular. Cephalosporins cause positive direct antiglobulin tests in a small percentage of patients either by the same mechanism as penicillins or by modification of the red cell membrane leading to nonimmunologic absorption of serum proteins. Hemolytic anemia has been reported only rarely. A few drugs (notably alpha methyldopa) cause the development of autoimmune hemolytic anemia. Knowledge of clinical manifestations and laboratory aids to diagnosis is necessary to distinguish immunohematologic abnormalities caused by drugs from other causes.