serologice

Serology, or serological testing, is the branch of medical laboratory science that studies the humoral component of the immune system by detecting antibodies or antigens in blood serum or other body fluids. It provides information about exposure to pathogens, immune status, and the presence of certain autoimmune or alloimmune conditions.

Specimens typically used are serum or plasma, but other fluids can be tested. Results can be qualitative (positive or negative) or quantitative, reporting antibody titers or antigen levels. Serology underpins many diagnostic and surveillance activities across infectious disease, transfusion medicine, and vaccinology.

Common serological techniques include enzyme-linked immunosorbent assay (ELISA), Western blot, immunofluorescence assays, agglutination and precipitation tests, and rapid diagnostic tests based on lateral flow immunoassays. Neutralization tests and avidity assays provide information about antibody functionality and timing of infection.

Applications span diagnosis of infections such as HIV, hepatitis B and C, syphilis, and coronavirus diseases; evaluation of immune responses after vaccination; autoimmune serology (for example antibodies associated with systemic lupus erythematosus); blood donor screening; and epidemiological surveillance.

Interpretation depends on clinical context and timing. Early infections may yield false-negative results due to the window period; serological cross-reactivity can cause false positives; immunocompromised patients may have blunted responses. Serology is often used alongside molecular tests to confirm active infection.

Historically, serology emerged in the late 19th and early 20th centuries with the discovery of antibodies and the development of the first immunoassays. Landmark advances include the identification of blood groups and the refinement of antibody–antigen testing, which matured into the broad array of serological tools used today.