A patient is O positive and his serum is agglutinating all screening and panel reagent cells at room temperature. His autocontrol is positive at room temperature also. The patient may have an antibody to a high incidence antigen. One possibility is that he may have a clinically insignificant autoanti-I. How could you prove that the patient has an anti-I antibody?

The direct ELISA test requires     only one antibody     only one antigen     both primary and secondary antibody     only secondary antibody conjugated with enzyme system

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Method: 1. 96 well plates are coated with an antigen. Sites unoccupied by the antigen are blocked with a blocking buffer to prevent non-specific binding of sample. Draw this below: 2. Serum samples are added and incubated to allow specific antibodies to bind to specific antigen. Antibodies that do not recognize and bind specifically to the antigen remain unbound. Draw this below: Positive sample Negative sample 3. Non-specific antibodies that do not bind to the antigen are washed away. Draw this below. Positive sample Negative sample 4. An enzyme labeled (e.g. alkaline phosphatase or horseradish peroxidase) secondary antibody is incubated with the samples and binds tightly to sample antibody. Draw this below.