Aim To evaluate the role of CD40 ligands(CD40L),pregnancy-associated plasma protein A(PAPP-A)and malondialdehyde-modified low density lipoprotein(MDA-LDL)in the development of plaque disruption.Methods Eighty-five patients with coronary heart disease(CHD)and twenty-five controls were collected in this study.All patients underwent coronary angiography.The angiographic morphology of plaques was analyzed.According to the morphologic types of plaque,the patients with CHD were divided into type Ⅰ(smooth borders)group(n=31)and type Ⅱ(irregular lesions)group(n=35)and type Ⅲ(long lesions)group(n=19).Plasma CD40L,PAPP-A and MDA-LDL were measured in all patients.Results Plasma CD40L,PAPP-A and MDA-LDL in type Ⅱ group were significantly higer than those in the control group,type Ⅰ group and type Ⅲ group(p<0.01).The plasma levels of CD40L and PAPP-A had a significant positive correlation in the patients with type Ⅱ CHD(r=0.446,p<0.01).The plasma levels of MDA-LDL didn't correlate to low density lipoprotein(LDL)and high density lipoprotein(HDL)in the patients with typeⅡCHD(p>0.05).The plasma levels of MDA-LDL and PAPP-A had a significant positive correlation in the patients with type Ⅱ CHD(r=0.630,p<0.01).Conclusions Plasma levels of CD40L,PAPP-A and MDA-LDL increased in patients with coronary plaque rupture,CD40L and PAPP-A had a positive correlation,which indicated CD40L possibly facilitates the plaque rupture via upregulating the PAPP-A expression;MDA-LDL and PAPP-A had a positive correlation,which indicated the oxidative stress is likely to either induce or intensify inflammatory action,and may be co-effect with inflammation facts to cause or accelerate plaque rupture.