Abundant and Crucial in the Complement System C3, the most abundant protein in the complement system, plays a central role in innate immunity with serum levels approximately 1.3 mg/ml. As a critical component of the complement system, which includes three pathways, C3 and its fragment C3a are integral to both the classical, alternative, and lectin pathways of complement activation.
The Activation and Function of C3/C3a
The activation of C3 leads to the formation of various products, including C3a, which bear neo-epitopes absent in their native form. Monoclonal antibodies like the 2898 are instrumental in directly quantifying these activation stages. Tissue-specific synthesis of C3, responsive to numerous stimulants, further underscores the dynamic nature of C3/C3a in immune responses. Moreover, a deficiency in C3 can predispose individuals to frequent bacterial infections, emphasizing the protective role of C3/C3a in the immune system. This is particularly evident in conditions like ulcerative colitis and chronic inflammatory bowel disease, where abnormal C3 deposition is observed.
Proteolytic Cleavage and the Stability of C3a
Enzymatic proteolysis of C3 releases the anaphylatoxin C3a and C3b. The C3a fragment, a protein of 74 amino acids, is inherently short-lived, quickly transforming into the more stable form, C3a-desArg. This transformation makes C3a-desArg a reliable marker for complement activation levels in test samples, showcasing the significance of C3/C3a in immunological assays.
C3a’s Role in Inflammatory Responses
C3a is a potent mediator in local inflammatory processes. It induces smooth muscle contraction, increases vascular permeability, and triggers histamine release from mast cells and basophils. C3a mediates inflammation, impacting conditions like sepsis, ischemic heart disease, and autoimmune diseases.
The comprehensive understanding of C3/C3a, from its detection by monoclonal antibodies to its role in immune responses and diseases, is crucial. The study of C3/C3a not only illuminates key aspects of the immune system but also aids in the development of targeted therapeutic interventions.
Not sure which C3 antibody to use?
With numerous options available, it is essential to select the right C3 antibody to ensure the success of your research. We designed a guide to assist you in making an informed decision:
Go to our C3 researcher’s guide and choose the right antibody
Immuno assays, Western blot
W: A reduced sample treatment and SDS-PAGE was used. The band size is ~95 and 8.2 kDa for C3 and C3a respectively (Ref.1).
For Western blotting, dilutions to be used depend on detection system applied. It is recommended that users test the reagent and determine their own optimal dilutions. The typical starting working dilution is 1:50.