TNF and tetanus: Heat-treated IgG (up to 57 °C) was capable of binding various antigens (tetanus toxoid (TT), diphtheria toxoid (DT) and Epstein Barr Virus nuclear antigen 1 (EBNA 1) (Fig 5a), and heat-treated IFX retained the ability to bind TNF but was somewhat less tolerant to incubation at 57 °C due to precipitation (Fig 5b).