IMMUNOLOGY

Detailed explanation-1: -Foreignness. The degree of immunogenicity depends on the degree of foreignness, i.e., The greater the phylogenetic distances between two species, the greater the structural (and therefore the antigenic) disparity between them.

Detailed explanation-2: -Foreignness-The immunogen must be foreign to the host. Immune responses take place only to substances that are not normally present in the body or normally exposed to the cells of the specific immune system. Under normal conditions, the immune system will discriminate between “self” and “non-self".

Detailed explanation-3: -Antigens that are easily phagocytosed are generally more immunogenic. This is because for most antigens (T-dependant antigens, see below) the development of an immune response requires that the antigen be phagocytosed, processed and presented to helper T cells by an antigen presenting cell (APC).