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Complement activation plays an important role in ischemia/reperfusion (I/R) injury. The objective of the present study was to detect the presence and mechanism of complement activation in patients who underwent carotid endarterectomy (CEA).Complement activation products C1rsC1-inhibitor, C4d, C3a and SC5b-9 and concentrations of C-reactive protein (CRP) were measured in samples serially taken from 16 patients with eversion CEA and 10 with carotid artery stenting (CAS) in the first 24h post-surgery/intervention. MBL2 genotypes were also determined.In patients with CEA an intense increase in C3a levels were observed immediately after surgery (p0.001), accompanied by a slight elevation in SC5b-9 levels (p0.05). C3a levels remained elevated until 4h post-surgery, compared with the baseline values and with CAS patients. Peak C3a levels correlated with the time of carotid clamping (r=0.5921, p=0.02). No significant changes were detected in C1rsC1-inhibitor or C4d levels following CEA, and we found no association between the generation of C3a and MBL2 genotypes or CRP levels. Complement activation was not present in patients with CAS.Early complement activation follows CEA and correlates with the time of I/R injury. The lack of C4d generation suggests the role of the alternative and not the lectin pathway in the process.

The presence of autoantibodies to C1-inhibitor (C1-INH-Abs) is a hallmark of acquired C1-inhibitor deficiency. However, only scarce data are available on their prevalence in hereditary angioedema (HAE). In a prospective study performed between 2001 and 2004 in 95 patients with Type I or II HAE, serum samples were taken one to three times a year and clinical status of the patients was registered. Serum samples were tested for total activity of the classical pathway, C1q, C3, C4 and C1-inhibitor (C1-INH) concentration and activity levels, as well as the presence of IgG, IgA and IgM type anti-C1-inhibitor antibodies (C1-INH-Ab). Fifty-four healthy age and gender matched persons served as control. Significant differences between the patients and controls in the occurrence of elevated (2S.D. higher than mean of control) C1-INH-Abs titers was found only in the case of IgM type C1-INH-Abs. Elevated (>4.22AU/ml) IgM C1-INH-Abs levels were found in 31 and 4% of the patients and controls, respectively (p

In the first part of the review article authors summarize our knowledge on the role of complement in atherogenesis and the development of I/R injury as well as the complement activation products which contribute to these pathological processes. In the second part of the review authors highlight the complement dependent processes which participate at the pathomechanism of cerebrovascular diseases, the development of cerebral infarct in ischemic stroke and the restenosis which may occur a part of the patients who underwent eversion endartectomy operation. Literature data and the recently published data of the authors' group indicate that the complement system is strongly activated at the onset of the ischemic stroke and the extent of this activation is positively correlated with the bad outcome of the disease. This observation may be one of the starting points of the introduction of the complement activation-inhibiting therapy in ischemic stroke.

In order to study if in patients with hereditary angioedema (HAE), copy number of the two genes (C4A and C4A) encoded in the central region of main histocompatibility complex (MHC) influences the diagnostically important C4 serum concentration as well as the clinical course of the disease, we determined copy number of the complement C4A and C4B genes in DNA samples of 95 HAE patients and 246 healthy controls. Distribution of both the C4A and C4B copy numbers significantly (p = 0.0183 and 0.0318, respectively) differed between the two groups, the most marked difference we observed was the lower frequency of the high (3 or 4) C4A copy numbers in the patients. As it expected, the dosage of both C4A and C4B genes positively correlated to the longitudinally measured serum C4 concentrations. Moreover, we found an unexpected clinical correlation with the dosage of the C4B gene. The course of the disease was milder in the 9/95 patients carrying 3 or 4 copies of C4B gene, compared to the rest of patients, i.e. diagnosis was established at significantly (p = 0.0052) older age (36.0 (31.0–39.5)) years versus 20.5 (7.5–31.5 years), biyearly attack rate was significantly (p = 0.0145) lower (1.0 (0.0–11.0)) versus 11.0 (3.5–21.5), and the over-all activity of the classical pathway and the enzyme-inhibitor activity of the C1-inhibitor (C1-INH) was closer to the normal values. These observations indicate that high copy number of the C4B gene can be a protective factor against disease severity in HAE and therefore its determination is warranted.

The presence of autoantibodies to C1-inhibitor (C1-INH-Abs) is a hallmark of acquired C1-inhibitor deficiency. However, only scarce data are available on their prevalence in hereditary angioedema (HAE). In a prospective study performed between 2001 and 2004 in 95 patients with Type I or II HAE, serum samples were taken one to three times a year and clinical status of the patients was registered. Serum samples were tested for total activity of the classical pathway, C1q, C3, C4 and C1-inhibitor (C1-INH) concentration and activity levels, as well as the presence of IgG, IgA and IgM type anti-C1-inhibitor antibodies (C1-INH-Ab). Fifty-four healthy age and gender matched persons served as control. Significant differences between the patients and controls in the occurrence of elevated (2S.D. higher than mean of control) C1-INH-Abs titers was found only in the case of IgM type C1-INH-Abs. Elevated (4.22AU/ml) IgM C1-INH-Abs levels were found in 31 and 4% of the patients and controls, respectively (p0.001). Surprisingly, high titer IgM C1-INH-Abs were present with equal frequency in the 41 HAE patients ever treated with C1-INH concentrate and in the 54 C1-INH treatment naïve patients. In the latter group, strong positive correlation between the levels of the IgM C1-INH-Abs and the most severe disease (score 1) (p=0.0021) and the yearly attack rate (p=0.0173) were obtained. In addition, the levels of the IgM C1-INH-Abs exhibited strong negative correlation to the C1-inhibitor concentration and functional activity, total classical complement pathway activity, and a positive correlation to total IgM concentration. Taken together, these data indicate that IgM type C1-INH-Abs are present with highly elevated frequency in HAE patients irrespectively of the previous treatment with C1-INH concentrate. Most probable production of these autoantibodies is the consequence of the activation of complement and other plasma enzyme systems during HAE attacks. Determination of IgM C1-INH-Abs can be used as an activity marker in HAE.