Identifying antibodies. These are proteins made by a type of white blood cell in response to a foreign substance (antigen) in the body.
Investigating problems with the immune system. These include when the body's immune system attacks its own tissues (autoimmune diseases) and when a body's immune system is underactive (immunodeficiency disorders).
Determining organ, tissue, and fluid compatibility for transplantation
 

Common immunology and serology tests

Test

Uses

Immunoglobulins

These are proteins in the body that have antibody activity. Excessive amounts of these proteins may be caused by a variety of conditions including infection, autoimmune disorders, cancers, and chronic diseases. A lack of these proteins may be caused by many conditions including cancers, medicines, and chronic diseases 

Rheumatoid factor

Used to help classify arthritis and diagnose rheumatoid arthritis. Other tests are often used as well to classify and determine types of arthritis. 

HLA (human leukocyte antigens) typing

Tested to determine compatibility in organ, tissue, and bone marrow transplantation. Also tested to determine paternity, and to diagnose HLA-related disorders such as certain autoimmune conditions.