HP and infection: One of these proteins, haptoglobin (or its functional equivalent, i.e. PIT54; see Wicher & Fries, 2006), is produced and released by the liver as a response to cytokines released during infection (Baumann & Gauldie, 1994; Cray et al., 2009; Quaye, 2008) and by binding free haemoglobin from damaged erythrocytes, it prevents oxidative damage and removes iron needed for bacterial growth (Gutteridge, 1987; Langlois & Delanghe, 1996).