Positive Result Presented for New Optimized Complement Function Testing - Working to Measuring the True Level of Inhibition Achieved in Circulation

At the recent 10th International Conference on Complement Therapeutics the Exsera BioLabs Laboratory Director presented the first results from our work to re-optimize the complement functional assays to better detect the true level of inhibition achieved in circulation.  By revising the assays to utilize a dilution of only 1/2, as opposed to normal dilution of 1/40 or even 1/100, it was demonstrated that new optimized assay measured a level of 81% inhibition by a circulating complement therapeutic, where the standard assay only measured a 34% inhibition in the same serum sample.  This was data for the CH50 hemolytic assay, but in all four functional assays demonstrated that the ability to detect inhibition was better in the new optimized functional tests in comparison to the standard assays. 


There are special needs related to the use of functional complement assays for the use or development of complement inhibiting therapeutics.  All of the standard complement functional assays utilizes often very sizable dilutions of the patient or subject serum for the measurement.  This can lead to diluting out the true level of inhibition.  At Exsera BioLabs we are are optimizing both the traditional hemolytic as well as ELISA style assays to be accurate and robust with low serum dilutions.  Add to that that we are uniquely in offering both styles of testing, which puts Exsera in a unique position to help with your complement function testing needs. 

Complement Function Testing - Hemolytic or ELISA 

Assays of complement function can take a couple of forms.  There are the original assays that utilize red blood cells as surrogate target with the release of hemoglobin as the read-out.  These have been automated by filling synthetic liposomes with enzymes that can be read on a standard chemistry analyzer.  Now we have ELISA style assays that are run in a higher, through-up 96 well plate and rely on the deposition of the complement components on activating surfaces of the plate.  Each of these assays present certain advantages and trade-offs, but different assays may return different results.  This can vary by patient or by drug.  Because of this we at Exsera BioLabs have decided to use both the hemolytic and ELISA assays, allowing for comparison of results within one laboratory. 

Individual Component Functions

Sometimes it is important to look at the functionality of individual complement components, either to investigate a suspected complement deficiency or to assess inhibition of a component.  The total function assays depend on all the components being present and functional, and due to the relative abundance of the components your component of interest may not be the rate-limiting element.  To investigate the functionality of the individual components can be very helpful.  Exsera BioLabs is therefore bringing forward the individual hemolytic assays for C2, C3, C4 and C5 with C1, Factor B, Factor D, C6, C7, C8 and C9 soon to follow. 

In vitro Complement Inhibition Testing

With our extensive knowledge of complement function testing, we combine experience with the testing for in vitro activation or inhibition of complement.  By performing exposures of normal human or NHP serum with the test article of interest we can measure the level of complement activation or of complement inhibition.  By testing with two methods for complement function in one lab, we are able to compare the two methods to reveal any differences that might be returned from a reference laboratory.  For this testing we set up a custom protocol, so inquire and we can customize a plan for you.