We observed that genes which are up-regulated at any stage of murine lupus nephritis could be systematically divided into the following subgroups (Table 1): i. Receptors (the TLR7–9 and Clec4e); ii. Signalling molecules (Myd88, Muc13, Ly86, Nfkb, and Rel); iii. Co-stimulatory molecules (CD80/CD86); and iv. cytokines and interleukins (TNFα, IFNγ. The gene discussed is CD80; the disease is lupus nephritis.