Immune system

Immunoglobulin deficiencies are associated primarily with recurrent infections by extracellular bacteria, but those affected have normal responses to intracellular bacteria, as well as viral and fungal infections.
Immune system is subject to failure of some or all of its parts. This failure can have dire consequences. When the system loses its sense of self and begins to attack host cells and tissues, the result is autoimmunity.
A primary immunodeficiency may affect either adaptive or innate immune functions.