Hemagglutination Inhibition
•General concept:
•U a two-step procedure in which there is competition between
•      a reagent antigen (antigen-coated particle) and a soluble
•      test antigen (pt=s serum) for antigen-binding sites
•      on a reagent antibody.
•Procedure:
•U Step 1
•\ Reagent antibody + patient serum added together
•\ incubation period
•U Step 2
•\ Reagent antigen-coated particles added
•\ incubation period
•\ interpretation of reaction made