Research On The Association Between Macrophage Inhibitory Cytokine-1 And Type 2 Diabetes

PART ONE: THE QUANTITATIVE ASSAY OF MACROPHAGE INHIBITORY CYTOKINE-1 BY SANDWICH ENZYME-LINKED IMMUNOSORBENT ASSAYObjective: To develop the quantitative assay method of Macrophage Inhibitory Cytokine-1 (MIC-1) in human serum, by Sandwich Enzyme-linked Immunosorbent Assay (ELISA), combined with the spectrophotometry method. And to evaluate the accuracy, stability and repeatability of this method.Methods: Standards and serum samples were derivatized by immunoreactions, and the antigen-antibody complexes which could be determined in visible region were generated. Then, the absorbance of complexes were measured by spectrophotometry at 450nm. Plotting the absorbances for each standard on the y-axis against the concentrations on the x-axis, a best fit curve was drawn and sample values were extrapolated from the standard curve. By this quantative assay, 8 serum samples from healthy subjects and 8 serum samples from patients with T2DM were determined, then the intraassay and interassay coefficients of variation were calculated for evaluation.Results: At 20～25℃, within the linear range 7.813pg/mL～500pg/mL, correlation coefficients of standard curves were between 0.990～0.999. The intraassay and interassay coefficients of variation were 1.89～5.10% and 5.93-14.07%. And the recoveries were 98.0～101.6%.Conclusions: This quantitative assay method was proved to be good in accuracy, stability and repeatability, and its detectable linear range is large. It could be applied in quantitative determination of MIC-1 in human serum. PART TWO: THE PRELIMIARY RESEARCH ON THE ASSOCIATION BETWEEN MIC-1 AND TYPE 2 DIABETE MELLITUSObjective: To analyze the characteristics of serum MIC-1 concentrations in patients with type 2 diabetes mellitus (T2DM). And to research preliminarily on the association between MIC-1 and T2DM.Methods: 51 non-diabetic subjects and 49 diabetics were enrolled. Height, weight, waist and hip circumferences, blood pressure, fasting plasma glucose (FPG), fasting serum insulin (FINS) and blood lipids were measured. Serum MIC-1 concentrations were determined by the sandwich ELISA.Results: Serum MIC-1 were significantly elevated in type 2 diabetic group than in the control group: median (range), 588.05 (158.90-2050.60) versus 284.35 (64.40-1150.20) pg/mL (P<0.001). On the data of all subjects, linear correlation analysis showed that serum MIC-1 was positively correlated with age, gender, BMI, systolic blood pressure (SBP), waist and hip circumferences, triglycerides (TG) and FPG. A linear stepwise regression analysis indicated that serum MIC-1 was independently associated with age, FPG and gender.Conclusions: Serum MIC-1 concentrations were significantly elevated in patients with T2DM. Age, FPG and gender were independent determinants of serum MIC-1.