Turbidimetry Measures turbidity or cloudiness of a solution by measuring the amount of light PASSING THROUGH the solution. Soluble antigen and antibody join and once they join in sufficient amounts precipitate, results in cloudiness. The more cloudy the solution, the less light can pass through.
Nephelometry Measures SCATTERED light bouncing off antigen- antibody complexes.
Passive Immunodiffusion Reactions in gels Migrate towards each other and where they meet in optimal proportions form a precipitate. Single diffusion, single dimension Single diffusion, double dimension Double diffusion, single dimension Double diffusion, double dimension
Two-dimensional immunoelectrophoresis. Antigens are separated on the basis of electrophoretic mobility. The second separation is run at right angles to the first which drives the antigens into the antiserum-containing gel to form precipitin peaks; the area under the peak is related to the concentration of antigen.
Agglutination Inhibition Based on competition between particulate and soluble antigens for limited antibody combining sites. Patient sample added to reagent antibody specific for antigen being tested, if antigen is present it binds to reagent antibody. Reagent particles (latex or RBCs) coated with the same antigen are added, if antigen was present in the sample all reagent antibody binds to it so no antibody is present to react with antigens coating the particles