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 basem ent membranes during aging and may affect protein turnover. The purpos e of this study was to localize Maillard reaction products in intact l ens capsules and Descemet's membranes by immunoelectron microscopy to determine whether Maillard products accumulated with age and whether b asement membrane thickness increased to a similar degree, The monoclon al antibodies antiglucitollysine and antipyrraline were employed to de tect the products in native and glucose-treated bovine basement membra nes. The content of basic amino acids, furosine, and fluorophores (370 /440), as well as resistance to trypsin digestion showed that the base ment membranes formed significant quantities of Maillard products when incubated with 200 mM glucose in vitro (P < 0.05). Likewise, incubati on in 200 mM glucose resulted in at least a 4-fold increase in immunor eactivity (P < 0.001). Native basement membranes increased in thicknes s more than 2-fold with age (P < 0.001). Immunoreactivity varied simil arly in that bound antiglucitollysine increased approx. 2-fold and ant ipyrraline approx. 3-fold in old vs. young basement membranes, but the se differences were significant only in pyrraline immunoreactivity in the lens capsule (P < 0.01). Advanced products other than pyrraline ma y accumulate in Descemet's membrane since significant increases in flu orescence and resistance to trypsin were noted. These data suggest tha t the Maillard reaction may, to a small degree, contribute to basement membrane thickening.