Objective:To study the expression of CD40-CD40L system on rabbit aorta plaque and correlation with plaque stabil- ity during atherosclerotic process.Methods:50 healthy rabbits were derided into 10 groups in random:five controlled groups (C1～5 group)and five AS model groups(AS1-5 group).Rabbits in C1～5 group were fed on regular diets until 8 weeks

10 weeks.12weeks

14weeks and 16weeks to get the aorta specimen respectly.Correspondingly rabbits in AS1～5 groups were given high lipid diets continously until 8weeks

10weeks

12weeks

14weeks and 16weeks

during which each AS group was conducted balloon injury at the end of the first week to prumote the establishment of AS models.All the groups were detected serum CRP individually at beginning and before specimen obtained.Immunohistochemistry and special stain was used to detect the intima expression proportion of CD40

CD40L

MMP-1 as well as contant of collagen and lipid photographed under microscope and measured by computer.Then the collagen/lipid ratio were calculated.Finally correlation between CD40-CD40L expression and plaque stability were analyzed.Results:All atherosclerotic plaques were successfully established on all rabbits’abdominal aorta in the 5 AS groups.Compared with C1～5 groups correspondantly

the expression of CD40

CD40L

MMP-1 were significantly in- creased(P<0.01)in every AS medel group.Meanwhile serum CRP levels were higher than those of each C group(P<0.01)evi- dendy.The correlation between CD40-CD40L system and CRP as well as MMP-1 is positive.While negative correlation is between CD40-CD40L level and collagen/lipid ratio.Conclusion:The expression levels of CD40-CD40L on plaque lesions were increasingly high with atherosclerosis processing.High expression of CD40-CD40L system has close relation to plaque vulnerability.