Positive Control	Negative Control	Patient A	Patient B	Patient C	Assay Control
1.689	0.153	O.055	0.412	1.999	0.123

Above is ELISA data from three patients. Numbers are expressed as optical density at 450nm. The cutoff value indicating a positive result is 0.500. Optical densities of 0.300 to 0.499 are indeterminate and need to be retested. Values below 0.300 are considered to be negative. In most cases, a patient will be retested if the serum gives a positive result. If the ELISA retests are positive, the patient will then be retested by western blotting analysis.

Immunological Techniques
University of Arizona
Monday, October 6, 2008
douglas.lake@asu.edu

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