The fate of γL crystallins in rat lens during diabetic cataractogenesis as determined by a monoclonal antibody

We developed a monoclonal antibody against HPLC purified rat lens γL crystallins. This antibody was specific to both the polypeptides (19,000 and 21,000 daltons) which constituted the HPLC γ1 peak. Least reactivity was shown against γH (24,000b daltons). This antibody was used as a probe to detect the presence of and quantitate γ1 crystallins in lens soluble, insoluble and urea-insoluble fractions during diabetes. Utilizing a direct binding immunoassay (ELISA) we calculated the absolute quantities of γl crystallins present in these fractions. Our results show, in normal animals there was a minimal change in total quantities of γL crystallins in soluble fraction from 1 month to 5 months of age, but a slow accumulation of these crystallins in insoluble and urea-insoluble fractions was seen during the same period. Diabetes resulted in a depletion of γL crystallins from the soluble fraction, both in terms of relative proportion and absolute quantities. In insoluble and urea-insoluble fractions the relative proportions of these crystallins were increased dramatically up until 60 days followed by a decrease during 90-120 days of diabetes, whereas, the absolute quantities remained more or less steady after reaching the maximum on 60 days. Although the relative proportions of γL crystallins in the insoluble fraction seem to be less when compared to urea-insoluble fraction, the total quantity of these crystallins was much higher due to abundance of this fraction. These results demonstrate that the early diabetic cataract events (up to 60 days) were associated with selective insolubilization and association with membranes of γLcrystallins while the later stages of cataract seem to involve other crystallins.