IMMUNOELECTRON MICROSCOPIC ANALYSES OF MAILLARD REACTION-PRODUCTS IN BOVINE ANTERIOR LENS CAPSULE AND DESCEMETS-MEMBRANE

It has been hypothesized that Maillard reaction products form in basement membranes during aging and may affect protein turnover. The purpose of this study was to localize Maillard reaction products in intact lens capsules and Descemet's membranes by immunoelectron microscopy to determine whether Maillard products accumulated with age and whether basement membrane thickness increased to a similar degree, The monoclonal antibodies antiglucitollysine and antipyrraline were employed to detect the products in native and glucose-treated bovine basement membranes. The content of basic amino acids, furosine, and fluorophores (370/440), as well as resistance to trypsin digestion showed that the basement membranes formed significant quantities of Maillard products when incubated with 200 mM glucose in vitro (P < 0.05). Likewise, incubation in 200 mM glucose resulted in at least a 4-fold increase in immunoreactivity (P < 0.001). Native basement membranes increased in thickness more than 2-fold with age (P < 0.001). Immunoreactivity varied similarly in that bound antiglucitollysine increased approx. 2-fold and antipyrraline approx. 3-fold in old vs. young basement membranes, but these differences were significant only in pyrraline immunoreactivity in the lens capsule (P < 0.01). Advanced products other than pyrraline may accumulate in Descemet's membrane since significant increases in fluorescence and resistance to trypsin were noted. These data suggest that the Maillard reaction may, to a small degree, contribute to basement membrane thickening.