| C3b

Complement Fragment 3b (C3b) is the larger cleavage product of complement component 3 and a crucial mediator of innate immunity. This multifunctional protein plays a central role in host defense through its ability to opsonize pathogens, immune complexes, and apoptotic cells for phagocytic clearance. C3b serves as the structural foundation for C3 convertase complexes across all complement activation pathways: in the alternative pathway it binds Factor B to form C3bBb, while in the classical and lectin pathways it combines with C4b2b to create C4b2b3b. The amplification loop further incorporates additional C3b molecules into C3bBb to generate C3bBb3b. These enzymatic complexes drive the complement cascade by generating more C3b molecules, thereby linking pathogen recognition to downstream inflammatory and cytolytic responses. The potent activity of C3b is tightly regulated by complement control proteins like Factor H and Factor I to prevent inappropriate activation against host tissues. This delicate balance between activation and regulation makes C3b a pivotal component in maintaining immune homeostasis while effectively eliminating threats.
 

| Typical data

As the OD values of the standard curve may vary according to the conditions of the actual assay performance (e.g. operator, pipetting technique, wash technique or temperature effects), the operator should establish a standard curve for each test. Typical standard curve and data are provided below for reference only.

 

Concentration (ng/mL)	15	7.5	3.75	1.87	0.94	0.47	0.23	0
OD	2.22	1.56	0.92	0.63	0.42	0.25	0.18	0.08
Corrected OD	2.14	1.48	0.84	0.55	0.34	0.17	0.1	-

 

| Repeatability

Intra-assay Precision (Precision within an assay)：CV% < 10%; Inter-assay Precision (Precision between assays)：CV% < 10%
 

| Recovery

The recovery of Mouse C3b spiked at three different levels in samples throughout the range of the assay was evaluated in various matrices.

 

Sample Type	Range(%)	Average Recovery(%)
Serum(n=8)	84-101	95
Plasma(n=8)	92-106	103
Cell Culture Supernates(n=8)	96-108	105

 

| Linearity

Samples were spiked with high concentrations of Mouse C3b and diluted with Universal Diluent to produce samples with values within the range of the assay.

 

		Serum(n=4)	Plasma(n=4)	Cell Culture Supernates(n=4)
1 : 2	Range (%)	84-95	88-96	90-110
	Average (%)	91	93	96
1 : 4	Range (%)	89-103	87-108	105-114
	Average (%)	94	98	107