In 1967, Mayo Clinic’s Blood Bank adopted an automated method for its test procedure that detected serum antibodies to red blood cells. The device used in the new method was an AutoAnalyzer, which was similar in principle to those already used at the time in the Biochemistry laboratories.
The new method, said Dr. Howard Taswell, “offers a very simple, rapid, and efficient way of screening large numbers of serum samples for the presence of red blood cell antibodies. It also makes possible for the first time an objective and precise method of quantitation of these antibodies. The end result is increased safety in transfusions.”
The automated procedure for determining antibodies differed from the older manual method. It was economical of both time and materials and was adapted to give results expressed numerically as micrograms of antibody nitrogen.
For screening purposes, the AutoAnalyzer was set to handle 50 samples an hour. The sample of blood was automatically pumped through the apparatus, appropriate reagents were added, and the color reaction occurred was recorded as a curve. A peak indicated presence of antibodies in a given sample. The test was then repeated with positive samples at a slower rate (20 samples per hour) and the measurement of the height of a peak, related to a standard scale, gave the antibody content.