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Association between circulating immune complexes, complement C4 null alleles, and myocardial infarction before age 45
A K Lefvert1, A Hamsten, G Holm
1Immunological Research Laboratory, King Gustaf V Research Institute, Stockholm, Sweden.
Insights
Circulating immune complexes (CICs) were elevated in young myocardial infarction survivors. Genetic deficiencies in complement factor C4 were linked to higher CIC levels, suggesting a role in early heart disease.
Area of Science:
- Cardiovascular Medicine
- Immunology
- Genetics
Background:
- Premature myocardial infarction (MI) affects individuals under 45.
- The role of immune complexes and complement deficiencies in early-onset MI requires further investigation.
Purpose of the Study:
- To investigate the prevalence of circulating immune complexes (CICs) and complement factor C4 null alleles (C4Q0) in young MI survivors.
- To explore the association between CICs, C4Q0, and the risk of premature myocardial infarction.
Main Methods:
- A case-control study involving 100 young MI survivors and 90 healthy controls.
- Measurement of CIC concentrations and genotyping for C4Q0 alleles.
Main Results:
- Elevated CICs were found in 20% of patients versus 6.7% of controls.
- C4Q0 prevalence was similar in both groups, but CICs were more frequent in C4Q0 carriers, especially those homozygous for C4A*Q0.
- Lower LDL concentrations were observed in patients homozygous for C4A*Q0.
Conclusions:
- Genetic deficiencies in complement factor C4, particularly C4A*Q0, are associated with increased CICs.
- Elevated CICs linked to C4 deficiencies may contribute to chronic vascular damage and premature myocardial infarction.
Abstract:
One hundred patients who had survived a myocardial infarction before the age of 45 years and 90 age- and sex-matched healthy individuals were investigated for circulating immune complexes (CICs) and the presence of complement C4 null alleles (C4Q0). CICs were found in increased concentrations in 20% of patients and 6.7% of control subjects. Patients and control subjects had the same prevalence of C4Q0. CICs were present in all patients and in 36% of the control subjects homozygous for C4Q0. Patients and control subjects heterozygous for C4Q0 had CICs in 71% and 0%, respectively. The high prevalence and a high concentration of CICs were particularly associated with C4A*Q0. Patients homozygous for C4A*Q0 had concentrations of LDL that were lower than found in other patients. The increased concentration of CICs associated with genetic deficiencies of the complement factor C4 might thus be an additional etiological factor for the development of chronic vascular damage and premature myocardial infarction.