Figure 5.

Immunoneutralization of islet cell MIF inhibits insulin secretion. Anti-MIF antibodies decrease the first and second phase of glucose-induced insulin secretion by isolated pancreatic islets. Ten purified rat islets were incubated in a perifusion chamber and the glucose concentration of the perifused buffer was increased experimentally from 2.8 mM (−40 to +7 min) to 16.7 mM (+8 to +33 min) and then returned to 2.8 mM (+34 min) as shown. The results are expressed as the mean ± SEM of three separate perifusion experiments. Control, nonimmune IgG or anti-MIF IgG (each at 50 μg/ml) was added to the chamber from +2 to +24 min. The quantity of insulin released during the first phase (+8 to +15 min) and the second phase (+16 to +25 min) of insulin secretion showed a decrease after immunoneutralization of MIF from 1.17 ± 0.19 ng/ml to 0.71 ± 0.06 ng/ml and 0.74 ± 0.02 ng/ml to 0.51 ± 0.01 ng/ml, respectively (P < 0.01 and P < 0.001 for the first and second phases of insulin secretion, respectively; Student’s t test).