A simple method for the assay of guinea pig anti-insulin serum

Development and Characterization of Guinea Pig Anti-Insulin Polyclonal Antibody

Development and characterization of guinea pig anti-insulin polyclonal antibody against a target-specific insulin antigen. In India, an insulin immunogenicity kit for detecting insulin antibodies (neutralizing Nab) is an unmet medical need for diabetic patient's routine diagnosis. Type 1 diabetics rely on insulin injections daily basis for survival; if the body develops anti-insulin antibodies and neutralizes the exogenous recombinant insulin, glucose control is lost, and the patient eventually dies. Antibodies are excellent diagnostic reagents due to the specificity and sensitivity they provide in recognizing specific and unique target antigens. The paper describes the use of insulin as a target antigen and the development of target (insulin) specific antibodies in guinea pigs for use as a positive control for immunogenicity kit validation. Anti-insulin polyclonal antibody was raised against insulin in the Dunkin Hartley guinea pigs host. Anti-insulin antibody titer of all bleeds from four animals was tested using an indirect ELISA assay format. All four animals responded to the target-specific antigen but only one animal (#4) responded with a high-affinity antibody titer. The hyperimmune sera were purified using a protein A column. The purified anti-insulin antibody was characterized through SDS Page and western blot. The specificity, reactivity, and antibody binding efficiency were confirmed through immunoassays. Guinea pig anti-insulin polyclonal antibody developed in this study showed good specificity, reactivity, and efficiency in the immunoassays. This paper describes the development and characterization of anti-insulin antibodies for use as a control in developing a user-friendly insulin immunogenicity kit.

A simple method for the measurement of low levels of serum IgE

A simple method for the estimation of low serum IgE levels is presented. Radioimmunoassay often gives falsely high values because of the presence of non-specific factors in the serum when an excessive amount of serum is used in order to measure low serum IgE levels. Therefore the serum sample has to be diluted to minimize the influence of the non-specific factors and the lowest IgE level measurable in the serum is about 5 u/ml. In this study, pretreatment of the serum with cellulose powder was found to remove the non-specific factors that yield falsely high values. These factors were adsorbed almost completely onto cellulose powder when the serum IgE level was less than 100 u/ml. Thus, low serum IgE levels could be determined by radioimmunoassay using a sufficient amount of serum pretreated by cellulose powder. The lowest serum IgE level measurable by this method was as low as 0.5 u/ml and the low IgE level in neonatal serum could be determined with sufficient accuracy. By this method the geometric level of IgE in cord serum was 2.45 u/ml with a +/- 2 standard deviations range of 1.04 to 5.80 u/ml.

A possible role for the adenylcyclase system in insulin secretion

A possible role for adenylcyclase in insulin secretion was investigated. Isoproterenol, a predominantly beta-adrenergic agent, when mixed with an alpha-adrenergic blocking agent (phenoxybenzamine), stimulated insulin secretion from pieces of the rat's pancreas in vitro. Theophylline, caffeine, 3'5'-cyclic AMP, glucagon, adrenocorticotropin (ACTH), and thyrotropin (TSH), all of which are thought to act through the adenylcyclase systems in the liver and adipose tissue, also stimulated insulin secretion in vitro; oxytocin and vasopressin, which do not stimulate lipolysis in adipose tissue, were inactive. In all cases, stimulation of insulin secretion could not be detected when glucose was absent or present in only low concentrations (less than 100 mg/100 ml) and was maximal at high levels of glucose (300 mg/100 ml). When pancreatic tissue was obtained from normoglycemic rats and contained no detectable glycogen in the Islets, the stimulant effects of glucose and of theophylline were reduced or abolished by mannoheptulose and 2-deoxyglucose. When tissue was derived from rats infused for 8-10 hr with glucose and contained glycogen, theophylline, even in the absence of glucose, stimulated secretion and this effect was reduced by 2-deoxyglucose but not by mannoheptulose. It is suggested that the beta-cell contains an adenylcyclase system through which phosphorylase and possibly phosphofructokinase could be activated; and that insulin secretion could depend upon and be regulated by hormones and other substances which influence the rate at which glycolysis proceeds within the beta-cell.