An improved method for rapid layering of Ficoll-Hypaque double density gradients suitable for granulocyte separation

A simple technique is described to layer Ficoll-Hypaque double density gradients suitable for rapid isolation of human granulocytes using disposable plastic syringes and 20-gauge needles. The syringes without plungers were kept at 45 degrees angle initially at the top of the test tube, the tip of the needle touching the side of the test tube. While layering the gradients, the syringes were progressively adjusted at 3 different positions which enhanced the smooth flow by forming a continuous stream from the tip of the needle to the top of the lower gradient resulting in excellent interfaces without causing turbulence or inadvertent mixing. This method is useful particularly when unknown sera are screened against granulocytes or lymphocytes from a large number of normal donors.