A simple technique for quantitative measurement of erythrocyte settling patterns in hemagglutination inhibition tests...

A simple technique for direct quantitative evaluation of hemagglutination or hemagglutination inhibition tests used in immunologic proteo-hormone assay systems is described. The test is performed in calibrated glass capillaries (internal diameter 2.5...4 mm) at horizontal position. After sedimentation the non-agglutinated erythrocytes form two fine parallel stripes along the bottom of the capillaries. The distance between the stripes depends on the amount of additional free antigen brought into the system. It can be measured by the slit of a micrometer screw or a corresponding equipped microscope and might be used as y-variable for drawing calibration curves. At well standardized test conditions and for selected concentration ranges coefficients of variation between 10 and 15% can be achieved. So quantitative determinations can be made without serial sample dilutions to be prepared, covering concentrations ranges between 1 to 10.