What is the technique used to analyze the blood for specific antibodies?

The technique used to analyze blood for specific antibodies is serology. Serology is a branch of immunology that focuses on the detection of antibodies in serum, which is the liquid component of blood that remains after clotting. This method is widely used in diagnostic laboratories to identify infections, autoimmune disorders, and blood type, among other conditions.

To perform serological testing, a sample of blood is typically taken, and the serum is separated. Various assays, such as enzyme-linked immunosorbent assays (ELISA), Western blots, or agglutination tests, can then be employed to determine the presence and concentration of specific antibodies. The presence of antibodies can indicate previous exposure to pathogens, recent infections, or immune responses to vaccines.

Each of the other techniques listed serves different purposes. Cytology involves examining cells for abnormalities, histology examines tissues at the microscopic level, and immunohistochemistry combines pathology and immunology but is primarily used to locate specific proteins in cells or tissues rather than analyzing serum for antibodies. Therefore, serology is the most appropriate method for the purpose of analyzing blood for specific antibodies.