The immune system's primary role is to defend the body against harmful microorganisms, such as bacteria, viruses, and parasites, and to remove foreign substances from the body.

Humoral immunodeficiency is characterized by a deficiency in the production or function of antibodies, which are proteins that recognize and neutralize foreign substances in the body.

Common variable immunodeficiency (CVID) is the most prevalent primary immunodeficiency disorder, characterized by a deficiency in the production of antibodies, leading to recurrent infections.

Phagocytic immunodeficiency is characterized by a deficiency in the number or function of phagocytic cells, which are responsible for engulfing and destroying foreign particles and microorganisms.

Acquired immunodeficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV), which attacks and destroys immune cells, leading to a weakened immune system.

Cellular immunodeficiency is characterized by a deficiency in the production or function of T cells, which play a crucial role in cell-mediated immunity and the recognition and destruction of infected cells.

HIV infection is the most common cause of secondary immunodeficiency disorders, as the virus directly targets and destroys immune cells, leading to a weakened immune system.

Antibody titer tests are used to measure the levels of antibodies in the blood, which can help diagnose humoral immunodeficiency disorders.

Bone marrow transplant is the primary treatment for severe combined immunodeficiency (SCID), as it replaces the defective immune system with healthy immune cells from a donor.

NK cell deficiency is characterized by a deficiency in the production or function of natural killer (NK) cells, which play a role in innate immunity and the recognition and destruction of infected cells.

X-linked agammaglobulinemia (XLA) is caused by a mutation in the Bruton's tyrosine kinase (BTK) gene, which is responsible for the development and function of B cells.

Complement deficiency is characterized by a deficiency in the production or function of complement proteins, which play a role in the activation of the immune system and the destruction of foreign particles.

Intravenous immunoglobulin (IVIG) therapy is the primary treatment for common variable immunodeficiency (CVID), as it provides the body with antibodies to help fight infections.

Cytokine deficiency is characterized by a deficiency in the production or function of cytokines, which are small proteins that play a crucial role in regulating the immune response.

Wiskott-Aldrich syndrome (WAS) is caused by a mutation in the WAS gene, which is responsible for the production of a protein involved in the regulation of immune cell function.