We postulate that caspase-8 deletion in the neutrophils and monocytes of CreLysMCasp8flox/flox mice that enter the joint under inflammatory conditions may contribute to the differing responses to K/BxN serum-transfer-induced arthritis in CreLysMCasp8flox/flox and CreCD11cCasp8flox/flox mice. The gene discussed is CASP8; the disease is arthritic joint disease.