Used in immunological research to detect and quantify complement component C4a in biological samples. Helps assess activation of the complement system, particularly in studies related to allergic reactions, inflammation, and immune complex diseases. Commonly applied in research on asthma, anaphylaxis, and autoimmune disorders to understand the role of complement activation in disease progression. Provides a reliable method for measuring C4a levels in serum, plasma, or cell culture supernatants, supporting investigations into immune response mechanisms and therapeutic interventions.