Positive test controls include: Jurkat. Immunogen sequence: GAVVTLECED GYMLEGSPQS QCQSDHQWNP PLAVCRSRSL APVLCGIAAG LILLTFLIVI TLYVISKHRA RNYYTDTSQK EAFHLEAREV YSVDPYNPAS. CD21 (complement receptor 2, CR2, C3D receptor, EBV receptor) binds C3 complement f