Interestingly, we found that the increased severity of arthritis seen in the absence of IFN-γ and IL-4 was associated with increased bone and cartilage damage as compared with the anti-IFN-γ only group, despite the fact that both groups showed a similar degree of synovitis and inflammatory infiltrate (Figures 4a and 4b). The gene discussed is IL4; the disease is arthritic joint disease.