Another hypothesis has been raised concerning the antibody engineering: even if human IgG1 has been described to interact with rat Fc gamma receptor of rat macrophages (Boltz-Nitulescu et al., 1981) – which we confirmed in this study by the ability of our anti-Crf antibodies to recruit several populations of immune cells –, this interaction may be insufficient to prevent the development of the infection. The gene discussed is CRH; the disease is infection.