I'm assuming you are referring to the CD4 protein on the surface of T-cells. If that's the case, AFAIK, there isn't a cost effective way yet. I remember a single sample cost about $250. Synthetic surface can be used, but it is not as effective as other methods (transgenic production I believe it was). But this was from a while back when we were studying VEG16, tumour growth and HIV, so there might have been some breakthrough since then.
|