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Angiography and complement activation. Evidence for generation of C3a anaphylatoxin by intravascular contrast agents
Insights
Radiocontrast agents can increase potent anaphylatoxin C3a levels in patients undergoing coronary angiography. Some agents significantly elevated C3a, while others did not, indicating variable responses.
Area of Science:
- Immunology
- Cardiology
- Pharmacology
Background:
- Radiocontrast agents are widely used in cardiovascular imaging.
- Anaphylatoxins, such as C3a, are implicated in hypersensitivity reactions.
- The direct impact of contrast media on C3a generation in vivo is not fully understood.
Purpose of the Study:
- To measure C3a levels in patients undergoing coronary angiography with radiocontrast agents.
- To investigate the in vitro capacity of different contrast agents to generate C3a.
Main Methods:
- Peripheral blood C3a levels were measured in 11 patients during coronary angiography.
- In vitro assays were performed using five different contrast agents and human serum.
Main Results:
- Elevated C3a levels were observed in 7 out of 11 patients.
- Three patients showed a four to tenfold increase in C3a.
- Four patients exhibited normal C3a levels.
- In vitro tests demonstrated significant variability among contrast agents in their ability to generate C3a from serum.
Conclusions:
- Radiocontrast media administration during coronary angiography can activate the complement system, leading to C3a generation.
- Patient responses to contrast agents vary, with some showing substantial C3a increases.
- Contrast agent composition influences C3a generation, suggesting potential for developing safer agents.
Abstract:
The potent anaphylatoxin C3a was measured in the peripheral blood of eleven patients receiving radiocontrast agents whilst undergoing coronary angiography. In seven patients C3a levels were raised during this procedure and in three of these the anaphylatoxin was increased between four and tenfold. In four patients C3a levels remained within the normal range. In vitro tests of five contrast agents revealed marked heterogeneity in their ability to generate C3a from serum.