It has been done.

Check Morrison and Kline J Immunol 1977; 118:362-368.

Otherwise, I don't know if you absolutely need to use LPS, but many people use zymosan to activate complement.

LPS is not good activator for a complement. In cells, if I'm not mistaken, it is working via TLR. Zymosan assay is a good alternative. Anyway, in serum you already  have activated complement, as it is additionally activated via coagulation cascade. 

Hi!

It depends on which complement pathway you want to activate. LPS and zymosan act on the alternative pathway, Actually, LPS is used in commercial alternative pathway ELISA tests (WIELISA). Aggreageted IgG/IgM or mannose are the best if you are interested in classical or lectin pathway, respectively.

Thank you for your answers! I am interested in activating the alternative pathway. I am wondering if LPS should be incubated with serum or with cells? Do you have any protocol for LPS-induced complement activation for serum? The only one I could find is from that study in 1977.

Dear Eleni,

Is there a particular reason on why you want to activate the AP in solution? Would a solid surface such as SPR or ELISA plate suffice? If not, one possibility would be to use zymosan as activator and veronal buffer supplemented with Mg/EGTA as activation buffer. (http://www.ncbi.nlm.nih.gov/pubmed/22851705). However keep in mind that human serum typically has antibodies against yeast, which can complicate your assay interpretation.

Another alternative is to immobilize LPS onto plastic surfaces, which is then bound by properdin/C3(H20) initiating AP cascade in the presence of Mg2+ and absence of Ca2+ (EGTA chelation). However not all LPS species can initiate AP cascades in given species. One good universal in my work has been salmonella enteridis S-type, which I have used to activate human, rat and mouse complement in ELISA setting.

You can find more information on the assay(s) and protocols through work of Marc Seelen (http://hdl.handle.net/1887/3738).

Good luck!