This product is shipped at ambient temperature. After arrival store, divided into small aliquots, frozen at or below -20 °C. Reconstitute the milk by adding 0.5 ml sterile distilled water. After careful mixing by inversion, allow to stand at ambient temperature for 5-10 minutes to reach equilibrium. The reconstituted milk should preferably be aliquoted and stored frozen at -20 °C. Working dilutions may be prepared by adding the required amount of phosphate buffered saline (PBS, pH 7.2) optionally containing 0.05% Tween and 1% (w/v) bovine serum albumin, should not be refrozen and preferably used within 24 hours. Repeated thawing and freezing should be avoided. If a slight precipitation occurs upon storage, this should be removed by centrifugation and will not affect the performance of the product.