There is only one immune system! The view from immunopathology

The generators of B and T cell diversity produce specificities for both autochthonous and exogenous paratopes. A wide variety of positive and negative, central and peripheral mechanisms has evolved to regulate the immune response. All potential immunogens are recognized by the system using the same set of 'rules', without discrimination between 'self' and 'nonself' or between the 'toxic' and the 'benign'. In every response, whether positive or negative, the factors mobilized and the balance between protection and damage depend upon the quality, quantity, location, and timing of immunogen presentation, as well as upon properties of the host.