H-69

Although many cell products are maintained at 4°C for years without loss of activity, shelf-life at 4°C is highly variable. For immediate use, short term storage at 4°C up to two weeks is recommended. For long term storage, divide the solution into volumes of no less than 20 ul for freezing at -20°C or -80°C. The small volume aliquot should provide sufficient reagent for short term use. Freeze-thaw cycles should be avoided. For concentrate or bioreactor products, an equal volume of glycerol, a cryoprotectant, may be added prior to freezing.

The optimal Ig concentration for an application varies by species and antibody affinity. For each product, the antibody titer must be optimized for every application by the end user laboratory. A good starting concentration for immunohistochemistry (IHC), immunofluorescence (IF), and immunocytochemistry (ICC) when using mouse Ig is 2-5 ug/ml. For western blots, the recommended concentration range of mouse Ig 0.2-0.5 ug/ml. In general, rabbit antibodies demonstrate greater affinity and are used at a magnitude lower Ig concentration for initial testing. The recommended concentrations for rabbit Ig are 0.2-0.5 ug/ml (IF, IHC and ICC) and 20-50 ng/ml (WB).