Immunologic effects of insulin lispro [Lys (B28), Pro (B29) human insulin] in IDDM and NIDDM patients previously treated with insulin.

Insulin lispro [Lys (B28), Pro (B29) human insulin] is a rapidly absorbed analog that has diminished tendency to self-associate. In four open-label, 1-year-long international randomized trials, we contrasted the immunogenicity of insulin lispro versus regular human insulin (RHI) in patients previously treated with insulin who had IDDM or NIDDM. Using a self-blank subtraction assay, we assessed sera for the presence of insulin-specific antibodies (ISA), insulin lispro-specific antibodies (LSA), and cross-reactive antibodies (CRA). Basal insulin needs were provided either with human ultralente (UL) or NPH insulins. After 2 to 4 weeks of therapy with RHI plus UL or RHI plus NPH, 50% of patients were randomly assigned to begin insulin lispro or continue on RHI. At baseline, few pretreated patients had LSA (0-4%) and approximately 10% had ISA, whereas 41-45% of patients with IDDM and 23-27% of patients with NIDDM had CRA (IDDM vs. NIDDM, P < 0.001). Within studies, no significant differences were noted over time in ISA, LSA, or CRA attributable to the type of short-acting insulin. When data were pooled, inconsistent changes were noted in ISA and LSA (LSA were greater in NIDDM vs. IDDM at baseline, P = 0.001, and ISA were greater in IDDM vs. NIDDM at 6 months, P = 0.007). Significant levels of CRA were more common in IDDM at all times (P < 0.001, P = 0.022, and P = 0.002 at baseline, 6 months, and 12 months, respectively). For patients receiving insulin lispro, no significant changes occurred in antibody status among IDDM and NIDDM patients throughout the study (became positive, remained positive, became negative, or remained negative). IDDM patients were more likely to develop or maintain CRA levels (P = 0.008 vs. NIDDM), whereas antibody levels were comparable among positive individuals. No evidence was noted that insulin lispro differs in immunogenicity from RHI in previously treated IDDM and NIDDM patients.

Presence of insulin autoantibodies as regular feature of nondiabetic repertoire of immunity.

With an ultrasensitive noncompetitive enzyme-linked immunosorbent assay (ELISA), we tested the hypothesis that the presence of insulin autoantibodies in nondiabetic individuals is a normal event. Plasma and peripheral blood mononuclear cells were obtained from 50 nondiabetic whites for determination of insulin autoantibodies by ELISA and radioimmunoassay (anti-insulin IgG [AI-IgG] and 125I-labeled insulin bound [%]), islet cell antibodies, anti-nuclear antibodies and rheumatoid factor, and HLA class II-type antigens (DR, DRw, and DQ). The range of 125I-insulin binding was significantly less than was seen in pretreatment sera from individuals with diabetes (from -0.4 to 0.4% vs. -0.8 to 7.7%, respectively, P = 0.001). Eighty-eight percent of these nondiabetic individuals had significant levels of AI-IgG with preferential binding to human insulin. The geometric mean of AI-IgG concentrations in individuals with significant levels was 180 pM. Binding to human insulin was seen in 88%, to pork insulin in 42%, and to beef insulin in 24% of individuals (P less than 0.001 overall; P less than 0.05 where more bound to pork than beef insulin). Binding of AI-IgG to human insulin-coated plates was substantially inhibited by preincubation with human insulin (median inhibition 57.6%) with little if any inhibition by glucagon, C-peptide, albumin, or IgG. Four individuals had highly specific human AI-IgG as shown by immunoaffinity studies. AI-IgGs were significantly higher in individuals with the HLA haplotype DR4,DRw53,DQ3 and lower in individuals with DR5,DRw52,DQ1 (P = 0.03 for both).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunologic aspects of human proinsulin therapy.

We investigated the immunogenicity of human proinsulin (HPI) when used as the sole or principal insulin agonist in insulin-naive patients with insulin-dependent (type I) and non-insulin-dependent (type II) diabetes mellitus. Sixty-one patients (13 type I, 48 type II) were treated with rDNA human insulin (NPH HI with or without regular HI) and 53 were treated with HPI (8 type I, 45 type II). At 6 mo, virtually identical levels of HbA1c (5.2 vs. 5.3%, P = NS) were achieved. However, regular HI was added less often to the treatment regimen in HPI-treated patients (16 vs. 32 patients, P less than .001). Overall, there was no significant increase in proinsulin-specific antibodies in either treatment group. However, 8 of 51 (1 transiently) patients in the HPI group developed low levels of binding of HPI (highest percentage bound was 5%). Two patients in the HI group developed very low levels of HPI binding (1.2 and 1.9%). Binding of HI (greater than 2.4%) was seen in both treatment groups; however, the prevalence of HI binding was less in the HPI group at 6 mo (39 of 60 in HI group vs. 20 of 51 in HPI group, P = .008). Concomitant treatment with regular HI did not affect the prevalence or level of binding of HPI or HI. We conclude that human proinsulin is a weak immunogen when used as the principal insulin agonist and may reduce both the formation of anti-HI antibodies and the need for concomitant therapy with regular HI.

Immunogenicity of recombinant DNA human insulin.

We postulated that human insulin of recombinant DNA origin would be a poor immunogen and might prove to be less immunogenic than purified pork insulin. Results are reported for 100 diabetic subjects not previously treated with insulin. Individuals completed the first 12 months of a clinical trial of human insulin of recombinant DNA origin. These patients are contrasted with 121 similar individuals who are taking part in a trial of purified pork insulin. Prior to therapy, species-specific binding of 125I human insulin and pork insulins and insulin bound to antibody were undetectable in all individuals. In patients treated with human insulin of recombinant DNA origin, binding of 125I human insulin increased to 10 +/- 1.2% at 12 months versus increases in binding of 125I pork insulin in pork insulin-treated patients to 12.6 +/- 1.4% (NS). Mean percentages of species-specific binding tended to reach a plateau in the human insulin-treated group but continued to increase in the pork insulin group (p less than 0.001). Median bound values were nil throughout in patients treated with human insulin, but increased to 52 mU/l in the pork insulin group with significantly less bound insulin seen in the former group at all visits (p less than 0.001). The percentage of individuals who remained antibody free at 12 months, as indicated by bound insulin, was 56% in the human insulin-treated patients and 40% in the patients treated with pork insulin (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)