If any organism produces immune response against its own healthy cells and tissue systems, then the phenomenon is known as Autoimmunity and the disease from such an aberrant immune response that results is termed an "autoimmune disease". Immunodeficiency and Autoimmunity: Clinical and laboratory characteristics of autoimmunity are presented in large numbers by immunodeficiency syndromes. Autoimmunity through perpetual immune system activation may be caused to clear infections in these patients by the decreased ability of the immune system. Autoimmune thyroid disease, autoimmune thrombocytopenia and inflammatory bowel are the multiple autoimmune diseases seen from common variable immunodeficiency. Diagnosis: It can be diagnosed on an accurate history and physical examination of the patient and even on certain abnormalities in routine laboratory tests. In many of the systemic disorders, specific autoantibodies can be detected from serological assays, whereas...