Abstract: Objective To study the association between the levels of urokinase-type plasminogen activator (uPA) in serum and late-onset Alzheimer's disease (LOAD). Methods ELISA was adopted to determine the concentration of uPA in serum of the 44 LOAD sufferers and 40 subjects from the control group. The polymerase chain reaction-restriction fragment length polymorphism ( PCR-RFLP) technique was used in detecting the polymorphism of the P141L polymorphisms of urokinase plasminogen activator gene (PLAU) in all cases, and to analyze the concentration of the uPA of different genotypes. Results The difference in the concentration of uPA in blood serum between the LOAD group and the control group was not significant (P>0.05), either was the difference among the singulorum degree of LOAD groups and the control group (P>0.05). The concentration of uPA in C/C genotype group and C/T genotype group were both higher than T/T genotype group, and the difference among the three groups was significant statistically (P<0.01). Conclusion The uPA level of LOAD sufferers in serum cannot be taken as the biomarker for the diagnosis of AD. Neither can it reflect the degrees of dementia. The concentration of uPA in T/T genotype group is lower than that in C/T and C/C group, indicating that the C→T mutation in exons 6 of PLAU gene may reduce the level of uPA, which might provide a new ideas to research on pathogenesis of AD.

Key words: urokinase plasminogen activator, Alzheimer's disease, enzyme-linked immunosorbant assay, polymerase chain reaction-restriction fragment length polymorphism