The principle of the test is based on the gel technique described by Yves Lapierre2 in 1985 for detecting red
blood cell agglutination reactions. The DG Gel 8 plastic cards are composed of eight microtubes. Each
microtube is made of a chamber, also known as incubator chamber, at the top of a long and narrow
microtube, referred to as the column. Buffered gel solution containing specific antibody (anti-A, anti-B, antiAB,
anti-D and anti-K) has been prefilled into the microtube of the plastic card. The agglutination occurs
when the red blood cell antigens react with the corresponding antibodies, present in the gel solution or in the
serum or plasma sample (in the case of reverse grouping test). The gel column acts as a filter that traps
agglutinated red blood cells as they pass through the gel column during the centrifugation of the card. The
gel column separates agglutinated red blood cells from non-agglutinated red blood cells based on size. Any
agglutinated red blood cells are captured at the top of or along the gel column, and non-agglutinated red
blood cells reach the bottom of the microtube forming a pellet.