Serological Tests Dr. Mahmood Yaseen Hachim M.B.Ch.B, M.Sc. Medical Microbiology 2010 RAK Medical and Health Sciences University RAK College of Denatal Sciences Practical and Clinical Sessions

Serology refers to using antigen-antibody reactions in the laboratory for diagnostic purposes. Its name comes from the fact that serum, the liquid portion of the blood where antibodies are found is used in testing. Serologic testing may be used in the clinical laboratory in two distinct ways To identify unknown antigens To detect antibodies being made against a specific antigen in the patient's serum.

Antigen Antibody

Precipitation ( Soluble Antigen + Antibodies=Insoluble antigen-antibody complex) Ring test  is a precipitation reaction that takes place at the interface between two solutions, one containing antigen and one containing antibody. Single diffusion  is a precipitation technique, usually accomplished in a test tube, in which antibody (or antigen) in a gel is allowed to react with soluble antigen (or antibody) diffusing through it from a liquid interface.

Radial Immunodiffusion (Mancini )(Single diffusion)

Double diffusion

Immunoelectrophoresis (IEP)

Agglutinatin (Antigen on cells+antibodies=clumping)

Enzyme-linked immunosorbent assay (ELISA)  is the same test as RIA except that an enzyme is attached to an antibody instead of a radioactive label  involves measurement of a color change, which results from addition of substrate that is specific for the enzyme; the intensity of the color is proportional to the amount of antigen detected in the sample.

Negative ELISA TestPositive ELISA Test