Hi, I usually test the C activation through an ELISA assay. Be aware that not only the classical pathway, but all the three may be involved in destroying your epithelial cells. The project that you're working on seems really interesting, so that I'm wondering if might be possible to collaborate. We can, for sure. The group I recently joined has a.strong experience in the C sistem an C-related disease. Let me know your plans. 

Hi,

So in principle you are interested whether autoantibodies result in complement mediated cytotoxicity of particular cells of thymic cortex?

It depends whether you want to see the effect in vivo or do you have these cells or equivalent cell lines available in vitro? 

If you are restricted to looking the effect of complement in vivo, I am afraid that you will need to use either complement deficient animals, or pathway specific inhibitors to disseminate the contribution of complement after you have introduced the purified autoantibodies to the animals. 

You could also test whether your purified autoantibodies can trigger CDC in vitro. Although for this, you would need a cell line expressing your target of interest. The CDC requires IgG hexamerization, which is a bit of a hit-and-miss with rigid surfaces such as ELISA.