I am reading lots of papers for my diss at the moment and I need to cite the sentence: "Addition of CD70 transfectants to ... B cells ... augmented ... by about twofold as compared to that of mock tranfectants." I know what it means, but it would be easier for me to have ONE word for it and not to have to explain it in a long sentence.
Without knowledge of context I assume that "transfectants" means cells which express your gene of interest upon transfection. Thus, I would translate your phrase: "Ko-Kultur (?) mit CD70+ Zellen erhöhte die ... von B-Zellen um den Faktor 2 gegenüber der Ko-Kultur mit kontrolltransfizierten Zellen." In general I would tend to avoid any anglicisms in your thesis if possible (but a northern-blot is a Northernblot and a microarray is a Microarray ;-) ).