In 1984 a serum repository for HIV testing was established. The task of the repository was to collect and store serum samples from blood donors in four blood transfusion units located in four major risk areas for AIDS, namely New York, San Francisco, Miami, and Los Angeles. Blood was obtained from the New York Blood Center in New York City, the Irwin Memorial Blood Bank in San Francisco, the Red Cross in Los Angeles, and the American Red Cross, South Florida Region, in Miami. The purpose of the repository was to determine the outcome of the transfusion of blood components retrospectively found to show HIV infection of the donor. The collected sera were separated, indexed, frozen, and stored.