What component of blood is primarily examined in a serology test?

Serology tests primarily examine blood serum because serum is the component of blood that contains antibodies and other proteins that are crucial for diagnosing various diseases, including infections and autoimmune conditions. During the process of serum preparation, whole blood is allowed to clot, and then the liquid portion is separated from the cellular components (red blood cells, white blood cells, and platelets). This serum contains immunoglobulins and other soluble factors that provide information about the immune response to antigens.

The focus on serum in serology is essential since it reflects the body’s immune response and contains specific markers that can be used to identify diseases or conditions. Other components of blood, such as red blood cells, white blood cells, and platelets, are not typically the focus of serological assays as they serve different roles in the body, mainly related to oxygen transport, immune response (in a more cellular context), and clotting, respectively. Thus, it is the blood serum that is of primary importance in serology testing.