Frequencies of certain complement protein alleles and serum levels of anti-heat-shock protein antibodies in cerebrovascular diseases

Background and Purpose-A strong correlation exists between the intensity of atherosclerotic alterations in different arteries. Marked differences exist, however, in the age and sex distribution and risk factors for coronary heart disease (CHD) and cerebrovascular disease (CVD). We therefore performed genetic and immunologic studies in patients with CVD. Methods-We studied 292 patients with CVD (stroke or transient ischemic attack) and as control either 198 healthy blood donors and 485 healthy elderly (aged >60 years) people (genetic study) or 94 blood donors aged 45 to 60 years and 49 healthy elderly (aged >60 years) people (anti-heat-shock protein [hsp] measurements). Allele frequencies of 3 genes (C4A, C4B, and C3) encoding proteins of the complement system were determined by electrophoresis and immunofixation. Serum concentration of autoantibodies against 60-kDa heat-shock protein (anti-hsp60) was measured by the enzyme-linked immunosorbent assay method. Results-Marked differences were observed between CVD patients and controls in the genetic studies. In the CVD patients aged >60 years, the frequency (11.3%) of the deficient allele of the C4B gene (C4B*Q0) was significantly (P=0.0003) higher than that of the healthy controls (5.4%). By contrast, in the group aged 45 to 60 years, the frequency of the C4B*Q0 allele was lower in patients than in controls. Serum concentration of anti-hsp60 in the CVD patients did not differ from control values. Conclusions-In previous studies C4B*Q0 frequency was reported to be higher in CHD patients aged 45 to 60 years than in aged-matched controls. Moreover, high anti-hsp60 levels were found in CHD patients. These findings contrast with our present report of lower frequency of C4B*Q0 in CVD patients. Therefore, genetic and immunologic factors may at least partly explain the differences between the natural history and risk factors of CHD and CVD.